Joint-portion processing device for image data for use in an image processing apparatus

ABSTRACT

An image processing apparatus includes a joining-portion processing section for combining partial images that have been read in a divided manner. Focused on partial document data predeterminately specified among a plurality of partial document data stored in an image memory, the joint-portion processing section performs a recognizing operation on the joints, a positioning operation and other operations beginning with the proximity of the specified partial document data. The partial images are then combined together to form one complete image. For example, in the case of copying an original document, which is of a size too large to be copied in One operation, on one sheet of paper in a reduced manner, it becomes possible to eliminate time consuming tasks such as trimming and pasting of the partial documents as well as calculating of the reduction rate. Thus, the efficiency of the operation is improved, and by specifying the partial document data from which the operation is started, it is possible to join the partial images accurately irrespective of the order of inputting the partial documents.

This application is a divisional of application Ser. No. 08/153,897,filed on Nov. 17, 1993, now U.S. Pat. No. 5,452,105 the entire contentsof which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to image processing apparatuses, such ascopying machines, scanners, facsimiles, and printers, which are capableof automatically joining images, which have been read in a dividedmanner, and forming the joined image on a recording medium of a desiredsize.

BACKGROUND OF THE INVENTION

In order to combine a plurality of images together and to record thecombined image on one sheet of paper, an information recordingapparatus, such as disclosed in Japanese Examined Patent Publication No.33752/1981 (Tokukoushou 56-33752), is employed. In this apparatus, imagedata for each page is stored as each independent data. For example, ifimage data of 4 pages of A-4 size are respectively stored as independentdata, the information recording apparatus is capable of reducing thestored image data respectively and combining them together so as to formthe combined image on one sheet of paper of A-4 size.

Here, in the case of applying the above-mentioned operation to anoriginal document of a large size which cannot be read through onecomplete scanning, the image of the original document is read in adivided manner. These divided images are stored as divided image dataincluding of a plurality of pages. However, in the above-mentionedapparatus, since the image data are stored as individual data forrespective pages, there is no correlation between those individual datafor respective pages. For this reason, even if the divided image dataare reduced for the respective pages, and combined together, the dividedimages cannot be joined together into the original form.

Therefore, in the case of copying an original document having a sizelarger than, for example, the document platen on one sheet of paper of adesired size, the following method is used:

(1) An original document is divided into a plurality of regions, andthose regions are respectively reduced and copied to form dividedoriginal documents;

(2) The divided original documents are trimmed and pasted to form onesheet of original document;

(3) The original document thus joined together is again copied.

However, in such a method including the above (1) through (3),troublesome and time consuming tasks are required in positioning andpasting the divided original documents manually, and in calculating areduction rate in accordance with the size of copy sheet whereon acomplete copied image is formed. Further, even if the reduction rate isset uniformly in obtaining the divided original documents, slight errorsare inevitable in the reduction rates for the divided originaldocuments. Therefore, offsets might be produced at the joints when thosedivided original documents are joined together.

Meanwhile, Japanese Laid-Open Patent Publication No. 331567/1992(Tokukaihei 4-331567) has disclosed a digital image forming apparatuswherein in the case of copying an original document that is larger thanthe copiable size, a plurality of image data that have been individuallyread are combined and compiled, and are reduced into a copiable size.

In this apparatus, if the copying operation is performed on an originaldocument that is, for example, twice as large as the readable size, theoriginal document is divided into two equal portions, and the portionsare successively read. Then, the image data thus read are reduced, ifnecessary. In this case, upon reading the image data, the originaldocument to be read later is placed on the document platen in a statewhere it is rotated by 180 degrees with respect to the original documentthat was read previously. Then, the image data that was read firstly isrotated by 90 degrees, while the image data that was read secondly isrotated by 90 degrees in the direction opposite to the first rotation,and both of the image data are combined together. Thus, a combined imageis formed on one sheet of paper. Therefore, with such a digital imageforming apparatus, the aforementioned troublesome and time consumingtasks are eliminated, and even in the case of copying an originaldocument larger than the size of the document platen, a copied image isformed on one sheet of paper of a desired size.

However, in such an digital image forming apparatus, since the imagedata are merely reduced, and merely rotated in the predetermineddirections, offsets might be produced at the joints in a combined image,thereby causing an adverse effect on picture quality. Further, in thecase where divided original documents of an image come up to a number ofpages, sufficient attention should be paid to the orientations of theoriginal documents or to other factors when they are placed on thedocument platen. This raises a problem related to low efficiency inoperation.

SUMMARY OF THE INVENTION

It is the first objective of the present invention to provide an imageprocessing apparatus which is capable of joining images that have beenread in a divided manner accurately in a short time, without causing anyadverse effects on the efficiency of operation.

It is the second objective of the present invention to provide an imageprocessing apparatus which is capable of reducing the amount ofinformation by which a joining operation is performed.

In order to achieve the first objective, the image processing apparatusof the present invention comprises:

(1) an input means for reading an image of an original document;

(2) a storage means for storing a plurality of partial images asrespective partial document data, the partial images having been read bythe input means in a divided manner; and

(3) a joint-portion processing means for recognizing reference data inresponse to an output of the input means, the reference data providing akey by which joints of the partial document data that have been storedin the storage means are retrieved, for recognizing the joints using therecognized reference data as a key, and for positioning the respectivepartial document data in accordance with the recognized joints.

With the above arrangement, the joint-portion processing meansrecognizes reference data in response to the output of the input means,and further recognizes the joints of the partial document data that havebeen stored in the storage means by using the reference data as a key.Then, the joint-portion processing means positions the partial documentdata in accordance with the recognized joints, and joins those partialdocument data, thereby forming document data that correspond to theimage of the original document.

More specifically, such reference data, which provide a key fordetecting the joints, include: for example, specific partial documentdata that are predeterminately specified; partial document data that arefirst stored in the storage means; data indicating a layout of thepartial document data that are set in accordance with the storagesequence of the partial document data and a divided condition of theimage; marks that are added to the partial document data so as toindicate the joints; and numbers that are added to the partial documentdata so as to determine the layout of the partial document data.

Therefore, in the case of using an original document that has to be readby the input means in a divided manner due to, for example, its largesize or other reasons, troublesome and time consuming tasks such astrimming and pasting the divided images are eliminated. This therebyimproves efficiency of the operation. Further, joints are recognizedfrom the partial document data using these reference data as a key, andthe joining operation is carried out in accordance with the joints.Therefore, even in the case where an image is divided into a number ofportions, the joining operation of the divided images is executedaccurately in a short time.

Moreover, a variable magnification means for variably magnifying thejoined document data into a desired size may be added to the abovearrangement. Thus, the joined image is readily reduced and formed on arecording medium of a desired size without the necessity of timeconsuming calculations on reduction rate.

Also, the image processing apparatus of the present invention isprovided with at least the following means in order to achieve the firstobjective:

(1) an input means for reading an image of an original document;

(2) a storage means for storing a plurality of partial images asrespective partial document data, the partial images having been read bythe input means in a divided manner; and

(3) a joint-portion processing means for obtaining specific image datacontaining features from the partial document data stored in the storagemeans by retrieving the partial document data stored in the storagemeans, and for selecting two partial document data in the order of theirincreasing number on the specific image data, comparing the specificimage data each other, recognizing joints at which the specific imagedata coincide with each other, and positioning the respective partialdocument data in accordance with the recognized joints.

With the above arrangement, the joint-portion processing means obtainsthe specific image data containing features from the partial documentdata by retrieving the partial document data stored in the storagemeans, and recognizes joints of the partial document data in the orderof their increasing number on the specific image data obtained. In otherwords, the two partial document data, which have virtually the sameamount of specific image data, have a high probability of coincidentspecific image data. Therefore, by performing the recognition ofspecific image data in accordance with the above order, it becomeseasier to find sides at which their specific image data coincide witheach other, even in the case where the sides contain few specific imagedata and it would be difficult to find joints from the sides.

Therefore, with the arrangement where the sequence of the joiningoperation is set in accordance with the amount of specific image datacontaining features, the joints are recognized in a short time and thelayout of the partial document data is easily determined without payingany particular attention to factors such as the sequence of inputtingdocuments and the orientations of the documents upon reading. Thisoccurs in the case of performing the joining operation on, for example,a number of original documents or on original documents havingcomplicated images. As a result, it becomes possible to carry out thejoining operation accurately and quickly, to improve the efficiency ofoperation in joining images, and to prevent offsets that would occur atthe joints. This ensures high quality in the images.

Also, the image processing apparatus of the present invention isprovided with at least the following means in order to achieve the firstobjective:

(1) an input means for reading an image of an original document;

(2) a storage means for storing a plurality of partial images asrespective partial document data, the partial images having been read bythe input means in a divided manner;

(3) a document-color recognition means for forming color datacorresponding to the respective partial document data by recognizing thecolors of the images read by the input means; and

(4) a joint-portion processing means for recognizing joints locatedbetween the partial document data stored in the storage means byretrieving the pattern of colors in the partial document data whilecomparing the color data formed in the document-color recognition meanswith the partial document data stored in the storage means, and forpositioning the respective partial document data in accordance with therecognized joints.

With the above arrangement, the colors of the images read by the inputmeans are recognized by the document-color recognition means. Further,the joint-portion processing means recognizes the joints by performingthe retrieving operation while comparing the color data formed in thedocument-color recognition means with the respective partial documentdata, thereby joining the partial document data together.

Therefore, even in the case of performing the joining operation on, forexample, a number of original documents or on original documents havingcomplicated images, a plurality of partial images are joined togetheraccurately and quickly without paying any particular attention tofactors such as the sequence of inputting documents and the orientationsof the documents upon reading. Thus, it becomes possible to improve theefficiency of the operation and to enhance the quality of the images.

Moreover, in order to achieve the first and second objectives, the imageprocessing apparatus of the present invention is provided with at leastthe following means:

(1) an input means for reading an image of an original document;

(2) a storage means for storing a plurality of partial images asrespective partial document data, the partial images having been read bythe input means in a divided manner; and

(3) a joint-portion processing means for recognizing joints locatedbetween the partial document data stored in the storage means and forextracting image data that lie in a direction orthogonal to the jointsof the partial document data and positioning the respective partialdocument data in accordance with the image data that lie in a directionorthogonal to the joints.

With the above arrangement, the joint-portion processing meansrecognizes the joints from the partial document data stored in thestorage means, and positions the respective partial document data. Inperforming this positioning, the image data that lie in a directionorthogonal to the joints of the partial document data are extracted, andthe positioning is performed so that the image data that lie in theorthogonal direction coincide with each other. This makes the change ofextracted image data clearer in the positioning as compared to the caseof extracting image data that have slant angles with respect to therespective joints and performing the positioning by shifting theextracted image data in a parallel or perpendicular direction.

Therefore, since the positioning of the partial document data is carriedout more effectively by the use of less image data, it becomes possibleto reduce the amount of information, and to shorten the time of thejoining operation. Thus, the original documents read in a divided mannerare joined together more accurately without causing any adverse effectson the efficiency of the operation.

Also, in order to achieve the first and second objectives, the imageprocessing apparatus of the present invention is provided with at leastthe following means:

(1) an input means for reading an image of an original document;

(2) a storage means for storing a plurality of partial images asrespective partial document data, the partial images having been read bythe input means in a divided manner;

(3) a black-document discrimination means for discriminating whether thepartial document data in question stored in the storage means aremono-color document data or color document data; and

(4) a joint-portion processing means for recognizing joints locatedbetween the partial document data stored-in the storage means and forconverting the color document data that have been discriminated by theblack-document discriminating means into mono-color document data andpositioning the respective partial document data in accordance with theconverted mono-color document data.

With the above arrangement, the joint-portion processing meansrecognizes the joints from the partial document data stored in thestorage means, and positions the respective partial document data sothat the respective images are smoothly joined together. In performingthe positioning of the partial document data, a discrimination is firstmade as to whether the partial document data in question stored in thestorage means are mono-color document data or color document data. Then,if the discrimination is made as color document data, the color documentdata are converted into mono-color document data.

Therefore, since the positioning of the partial document data is carriedout based on only the mono-color document data, it becomes possible toreduce the amount of information, and to shorten the time of the joiningoperation, as compared to the case where a decision is made for each ofthe colors, red, green and blue, in positioning the color document data.

Therefore, since the positioning of the partial document data is carriedout more effectively by the use of less image data, it becomes possibleto reduce the amount of information, and to shorten the time of thejoining operation. Thus, the original documents read in a divided mannerare joined together more accurately without causing any adverse effectson the efficiency of the operation.

Also, in order to achieve the first and second objectives, the imageprocessing apparatus of the present invention is provided with at leastthe following means:

(1) an input means for reading an image of an original document;

(2) a storage means for storing a plurality of partial images asrespective partial document data, the partial images having been read bythe input means in a divided manner;

(3) a joint-portion processing means for recognizing joints locatedbetween the partial document data stored in the storage means, and forenhancing the image data so that the outlines of images located in theproximity of the joints are made distinct, and for positioning therespective partial document data in accordance with the enhanced imagedata.

With the above arrangement, the joint-portion processing meansrecognizes the joints from the partial document data stored in thestorage means, and positions the respective partial document data sothat the respective images are smoothly joined together. Here, in thecase of using original documents of half-tone such as photographswherein outlines of images are in a diffused state, images obtained inthe proximity of the joints tend to be obscure upon positioning thepartial document data.

In order to solve this problem, an image enhancing operation, such asformation of outline data by emphasizing the density of edges or bymeans of a differential processing, is performed. This eliminates thediffused state of the images, and makes the outlines of the imagesclearer. Thus, it becomes possible to perform the positioning of thepartial document data more easily as well as more accurately based onthe enhanced image data.

Therefore, since the positioning of the partial document data is carriedout more effectively by the use of less image data, it becomes possibleto reduce the amount of information, and to shorten the time of thejoining operation. Thus, the original documents read in a divided mannerare joined together more accurately without causing any adverse effectson the efficiency of the operation.

For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a construction of an image processingsystem that is installed in a digital copying machine in one embodimentof the present invention.

FIG. 2 is an explanatory drawing that schematically shows theconstruction of the digital copying machine.

FIG. 3 is a flow chart showing the sequence of processes that arecarried out during a joining operation on partial document data in thedigital copying machine.

FIG. 4 is a schematic drawing showing partial document data that arestored in an image memory in the image processing system.

FIG. 5(a) is a schematic drawing which shows retrieving regions in thepartial document data; FIG. 5(b) is a schematic drawing which explainsthe positioning of the partial document data; and FIG. 5(c) is a planview showing a copied image that is obtained by joining the partialdocument data together.

FIG. 6 is a flow chart showing the sequence of processes that arecarried out during a joining operation on partial document data in thedigital copying machine of another embodiment of the present invention.

FIG. 7(a) is a schematic drawing which shows a layout of the inputtedpartial document data in the case of performing the operation shown inthe flow chart of FIG. 6; FIG. 7(b) is a schematic drawing which showsthe sequence of the joining operation; and FIG. 7(c) is a plan viewshowing a copied image that is obtained by joining the partial documentdata together.

FIG. 8 is a flow chart showing the sequence of processes that arecarried out during a joining operation on partial document data in thedigital copying machine of still another embodiment of the presentinvention.

FIG. 9(a) is a schematic drawing which shows one example of the inputtedpartial document data in the case of performing the operation shown inthe flow chart of FIG. 8; FIG. 9(b) is a schematic drawing whichexplains the positioning of the partial document data; and FIG. 9(c) isa plan view showing a copied image that is obtained by joining thepartial document data together.

FIG. 10 is a schematic drawing which shows one example of the partialdocument data whereon a plurality of marks are put, in the case ofperforming the operation shown in the flow chart of FIG. 8.

FIG. 11 is a flow chart showing the sequence of processes that arecarried out during a joining operation on partial document data in thedigital copying machine of still another embodiment of the presentinvention.

FIG. 12 is a schematic drawing which shows original documents on whichthe operation shown in the flow chart of FIG. 11 is carried out.

FIG. 13 is a schematic drawing which shows a layout of documents that isdetermined based on numbers that are put on the documents of FIG. 12.

FIG. 14(a) is a schematic drawing which shows retrieving regions in thepartial document data in the case of processing one portion of theoriginal documents shown in FIG. 12; FIG. 14(b) is a schematic drawingwhich explains the positioning of the partial document data; and FIG.14(c) is a plan view showing a copied image that is obtained by joiningthe partial document data together.

FIG. 15 is a flow chart showing the sequence of processes that arecarried out during a joining operation on partial document data in thedigital copying machine of still another embodiment of the presentinvention.

FIG. 16 is a flow chart showing the sequence of processes that arecarried out when the features of the original documents are extracted inthe flow chart of FIG. 15.

FIG. 17 is a schematic drawing which shows a layout of the partialdocument data in an image memory of the digital copying machine.

FIG. 18 is a schematic drawing which shows retrieving regions of thepartial document data that are stored in the image memory.

FIG. 19 is a flow chart showing the sequence of processes that arecarried out during a decision on coincidence or non-coincidence of thedocument data in the flow chart of FIG. 15

FIG. 20 is a flow chart showing the sequence of processes that arecarried out during a judgement as to the completion of all the dataprocessing in the flow chart of FIG. 15.

FIG. 21 is a schematic drawing which shows a layout of four images onwhich the operation shown in the flow chart of FIG. 15 is performed.

FIG. 22 is a flow chart showing the sequence of processes that arecarried out during a compensation for loss of data in the flow chart ofFIG. 15.

FIG. 23 is a schematic drawing which shows the partial document data inquestion on which the compensation for loss of data is carried out.

FIG. 24 is a flow chart showing the sequence of processes that arecarried out during a compensation for loss of data in the flow chart ofFIG. 15.

FIG. 25 is a flow chart showing the sequence of processes that arecarried out during a judgement as to the completion of all the dataprocessing in the flow chart of FIG. 15.

FIGS. 26(a) through 26(f) are plan views showing original documents onwhich the joining operation is carried out.

FIG. 27 is a schematic drawing which explains the positioning process ofthe partial document data in the joining operation.

FIG. 28 is a plan view showing a copied image that is obtained byjoining the partial document data together.

FIG. 29 is a block diagram showing a construction of an image processingsystem that is installed in a digital copying machine in still anotherembodiment of the present invention.

FIGS. 30(a) and 30(b) are plan views showing original documents on whichthe joining operation is carried out in the digital copying machine.

FIG. 31 is a schematic drawing which explains the positioning process ofthe partial document data in the joining operation.

FIG. 32 is a plan view showing a copied image that is obtained byjoining the partial document data together.

FIG. 33 is a block diagram showing a construction of an image processingsystem that is installed in a digital copying machine in still anotherembodiment of the present invention.

FIG. 34(a) is a schematic drawing which shows partial document datastored in the image memory of the image processing system; FIG. 34(b) isa schematic drawing which shows a state wherein positioning is made byextracting image data that lie in a direction orthogonal to the joints;FIG. 34(c) is a schematic drawing which shows the image data after thepositioning has been completed; and FIG. 34(d) is a schematic drawingwhich shows a reduced state of the document data that have been joinedtogether.

FIG. 35 is a flow chart showing the sequence of processes that arecarried out during a data extraction on each side of the partialdocument data in the operation shown in the flow chart of FIG. 15.

FIG. 36(a) is a schematic drawing which shows a state whereinpositioning is made on the partial document data by the use of imagedata that lie in a direction orthogonal to the joints; and FIG. 36(b) isa schematic drawing which shows a state wherein positioning is made bythe use of image data that have a slant angle with respect to thejoints.

FIG. 37 is a block diagram showing a construction of an image processingsystem that is installed in a digital copying machine in still anotherembodiment of the present invention.

FIG. 38(a) is a schematic drawing which explains a feature-extractingprocess by the use of color document data; and FIG. 38(b) is a schematicdrawing which explains a feature-extracting process by the use ofmono-color document data.

FIG. 39 is a block diagram showing a construction of an image processingsystem that is installed in a digital copying machine in still anotherembodiment of the present invention.

FIG. 40(a) is a graph which shows the change in density on the edges ofpartial document data before the application of an image-enhancingprocess; FIG. 40(b) is a graph which shows the change in density on theedges of the partial document data after the image-enhancing process hasbeen made by highlighting the edges; and FIG. 40(c) is a graph whichshows the change in density on the edges of the partial document dataafter the image-enhancing process has been made by means of adifferential processing.

FIG. 41(a) is a schematic drawing which explains the change in densityon partial document data as well as the positional variation on theimage in relation to the density before the application of animage-enhancing process; FIG. 41(b) is a schematic drawing whichexplains the change in density on the partial document data as well asthe positional variation on the image in relation to the density afterthe image-enhancing process has been made by highlighting the edges; andFIG. 41(c) is a schematic drawing which explains the change in densityon the partial document data as well as the positional variation of theimage in relation to the density after the image-enhancing process hasbeen made by means of the differential processing.

FIG. 42 is a schematic drawing which shows a formation of outline databy applying the image-enhancing process to the document data by means ofthe differential processing.

DESCRIPTION OF THE EMBODIMENTS

[EMBODIMENT 1]

Referring to FIGS. 1 through 5, the following description will discussone embodiment of the present invention.

As illustrated in FIG. 2, a digital copying machine, which is installedin an image processing apparatus in accordance with the presentembodiment, is provided with a document platen 27 made of a hard glassplate, etc. that is installed on the upper surface of a copying machinemain body 26. Below the document platen 27 is disposed a scanner unit(input means) 22. The scanner unit 22 is constituted of: a lamp unit 1;mirrors 2, 3 and 4; a lens unit 5; and a CCD (Charge Coupled Device)sensor 6. A reflected light beam, which is obtained by irradiating adocument (not shown) placed on the document platen 27 by the lamp unit1, is directed to the light-receiving face of the CCD sensor 6 throughthe mirrors 2, 3 and 4 and the lens unit 5, and detected therein aselectric signals.

A laser driver unit 7, which has a semiconductor laser, a polygon mirrorand an f-θ lens, is installed below the scanner unit 22. Image data ofthe document, which are detected by the CCD sensor 6 as the electricsignals, are temporarily stored in an image memory (storage means) 43installed in the image processing apparatus (see FIG. 1), which will bedescribed later. After having been subject to predetermined processingin the image processing apparatus, the image data are sent to the laserdriver unit 7. The laser driver unit 7 projects a laser beam from thesemiconductor laser in response to document data inputted thereto. Thelaser beam is diffracted by the polygon mirror in a constant angularvelocity, and the laser beam that has been subjected to the diffractionin the constant angular velocity is corrected by the f-θ lens so that itis further diffracted in a constant angular velocity on a photoreceptordrum 10.

A laser beam released from the laser driver unit 7 is reflected by themirrors 8 and 9 that are disposed in the light path, and projected ontothe photoreceptor drum 10, thereby forming an electrostatic latent imageon the photoreceptor drum 10. The photoreceptor drum 10 is capable ofrotating in the direction of arrow A as shown in FIG. 2. On theperiphery of the photoreceptor drum 10, are disposed a charger 16 forcharging the photoreceptor drum 10 so as to impart a predeterminedvoltage to its surface prior to an exposure executed by laser driverunit 7. Further, from the charger 16 along the rotation direction of thephotoreceptor drum 10, are installed in the following order: adeveloping device 28, a transferring belt 17, a cleaning device 21, anelectrostatic eliminating lamp 15, etc.

The developing device 28 includes a black developer vessel 11, a yellowdeveloper vessel 12, a magenta developer vessel 13, and cyan developervessel 14, and those developer vessels 11 through 14 respectively housetoners having corresponding colors. The developing device 28 suppliestoner onto the electrostatic latent image on the photoreceptor drum 10such that a toner image is formed thereon.

The transferring belt 17, which is provided in the form of an endlessbelt, is installed so as to move in the direction of arrow B in thedrawing, and one portion of the transferring belt 17 is pressed againstthe photoreceptor drum 10 such that the toner image on the photoreceptordrum 10 is transferred thereonto. After the tone image has beentransferred, the residual toner on the photoreceptor drum 10 is removedtherefrom by the cleaning device 21. Further, prior to the next charge,the residual electric potential on the photoreceptor drum 10 iseliminated by the electrostatic eliminating lamp 15.

On the paper-feeding side with respect to the transferring belt 17, areinstalled a resist roller 19, a feeding cassette 20, and a feeding tray23. In the proximity of the feeding cassette 20 and the feeding tray 23,are installed a feeding roller 24, a transporting roller 25, etc. Copysheets stored inside the feeding cassette 20 or on the feeding tray 23are supplied onto the transferring belt 17 at predetermined intervals bya resist roller 19.

Below the transferring belt 17, is installed a transferring roller 18which presses a copy sheet sent thereto from the resist roller 19against the transferring belt 17, and allows the toner image on thetransferring belt 17 to be transferred onto the copy sheet.

On the paper-discharging side with respect to the transferring belt 17,are installed a conveyer belt 30, a fixing device 31 and a dischargeroller 32. A copy sheet whereon the toner image has been transferred istransported to the fixing device 31 by the conveyer belt 30, and thetoner image is fused onto the copy sheet by heat. The copy sheet whereonthe toner image has been fused by heat is discharged outside the copyingmachine main body 26 by a discharge roller 32.

In the above arrangement, a color-copy (3 color copy) operation iscarried out in the following sequence. First, the charger 16 uniformlycharges the surface of the photoreceptor drum 10, and the scanner unit22 executes the first scanning. The document data detected by the CCDsensor 6 are processed in the image processing section, and are releasedfrom the laser driver unit 7 as a laser beam representative of yellowdata. The surface of the photoreceptor drum 10 is exposed by the laserbeam, and a electrostatic latent image for yellow-use is formed on theexposed portion of the photoreceptor drum 10. Then, yellow toner issupplied to the electrostatic latent image within the image region fromthe yellow developer vessel 12, and a yellow toner image is thus formed.

Next, the yellow toner image is transferred onto the transferring belt17 that is pressed against the photoreceptor drum 10. At this time,although some toner that has not been consumed in the transferringprocess remains on the surface of the photoreceptor drum 10, theresidual toner is scraped off by the cleaning device 21. Moreover, theelectrostatic eliminating lamp 15 eliminates the residual charge on thesurface of the photoreceptor drum 10.

After completion of the above processes, the charger 16 again chargesthe surface of the photoreceptor drum 10 uniformly, and the scanner unit22 executes the second scanning. The document data are processed in theimage processing section, and are released as a laser beamrepresentative of magenta data. The surface of the photoreceptor drum 10is exposed by the laser beam, and an electrostatic latent image formagenta-use is formed on the exposed portion of the photoreceptor drum10. Then, magenta toner is supplied to the electrostatic latent imagefrom the magenta developer vessel 13, and a magenta toner image is thusformed. Thereafter, this toner image is transferred onto thetransferring belt 17 so as to be superimposed on the former yellow tonerimage. After the cleaning device 21 and the electrostatic eliminatinglamp 15 have carried out the same processes as described earlier, thecharger 16 again charges the surface of the photoreceptor drum 10uniformly.

Then, the scanner unit 22 executes the third scanning, and anelectrostatic latent image for cyan-use is formed by exposing thephotoreceptor drum 10 with a laser beam representative of cyan data.Then, cyan toner is supplied to the electrostatic latent image from thecyan developer vessel 14, and a cyan toner image is thus formed.Thereafter, this cyan toner image is transferred onto the transferringbelt 17 so as to be finally superimposed on the former toner images.

A complete toner image on the transferring belt 17, which has beenformed by superimposing three toner images, is transferred onto a copysheet, and the complete toner image is fused onto the copy sheet byheat. Thereafter, the copy sheet is discharged out of the apparatus bythe discharge roller 32.

The sequence of processes described above is a sequence for carrying outa three-color copying operation. In the case of a four-color copyingoperation, a process using black toner in the black developer vessel 11is added to the above-mentioned sequence. In the case of a mono-colorcopying operation, black toner is supplied to the electrostatic latentimage from the black developer vessel 11, and the black toner image thusformed is transferred onto a copy sheet through the transferring belt17.

Referring to FIG. 1, the following description will discuss theconstruction, functions, etc. of the image processing section forsuitably processing the image data read by the CCD sensor 6 and forreleasing the data to laser driver unit 7.

As shown in FIG. 1, the image processing section, which executes colorreproduction according to the colors of a document and a joiningoperation on partial document data that have been obtained by reading animage in a divided manner as a plurality of partial images, isconstituted of a R.G.B level-adjusting section 40, an A/D convertor 41,a shading correction section 42, an image memory 43, a joint-portionprocessing section (joint-portion processing means) 48, a γ correctionsection 49, a black-document detection section 50, a masking section 51,a UCR(Under Color Removal)-BP(Black Print) processing section 52, asharpness filter 53, a variable magnification section (variablemagnification means) 54, a density processing section 55, acolor-balance adjusting section 56, tone processing section 57, etc.

In the image processing section, analog signals, that being, partialdocument data of R, G, B obtained from the CCD sensor 6, are compensatedfor their dispersions between R, G, B due to the respective sensors, andare then converted into digital signals in the A/D convertor 41.Thereafter, the partial document data are subjected to a shadingcorrection for correcting variations in sensitivity of the sensors foreach picture element, unevenness in brightness of the lens, etc. in theshading correction section 42, and are temporarily stored in the imagememory 43.

In this case, if a joining mode, which will be described later, isspecified, a plurality of documents that are to be joined for theirimages are successively scanned. Thereafter, partial images on therespective documents are separately stored in the image memory 43 asrespective partial document data. The partial document data are sentfrom the image memory 43 to the joint-portion processing section 48.

The joint-portion processing section 48 includes a joint recognitionsection 44, a data-arranging section 45, a positioning section 46, and acombination processing section 47. The partial document data inputted tothe joint-portion processing section 48 are first sent to the jointrecognition section 44 where the joints of the documents are recognized,and are then sent to the data-arranging section 45 where thecorresponding joints are arranged side by side with each other.Successively, the partial document data are sent to the positioningsection 46 where positioning is made so that images located at thejoints coincide with each other, and are then sent to the combinationprocessing section 47 where they are combined together.

After completion of the processing in the joint-portion processingsection 48, the document data are again inputted to the image memory 43.Here, as to the sequence of the operations in the above joint-portionprocessing, its detailed explanation will be given later.

Together with data released from the black-document detection section 50for making a discrimination between mono-color copy and color copy, thedocument data released from the image memory 43 are inputted to theγ-correction section 49 where a γ-correction is executed so as to adjustcontrast and brightness. Successively, the data of R, G, B, which havebeen subjected to the γ-correction, are converted into data of C, M, Y(Cyan, Magenta, Yellow) by executing suitable calculations in themasking section 51. In the UCR-BP processing section 52, the C, M, Ydata of the document are subjected to the UCR processing for removinggrey components from toners of three colors, C, M, Y, and for replacingthem with black toner, as well as subjected to the BP processing foradding black toner to the toners of three colors. Thus, B_(K) (black)data are added to the C, M, Y data of the document.

The sharpness filter 53 emphasizes the sharpness of the C.M.Y.B_(K) dataof the document. Further, the variable magnification section 54 and thedensity processing section 55 execute suitable processing on thesubsequent data so as to impart a specified size and density to theimage. The color-balance adjusting section 56 and the tone processingsection 57 respectively execute the balance adjustments and toneprocessing on the respective colors, and the subsequent data areinputted to the laser driver unit 7.

In the digital copying machine of the present embodiment which isprovided with the image processing section having the above arrangement,one document which contains the most outstanding features or which formsthe center of the image is preliminarily specified among a plurality ofdocuments whose images are to be joined together, and the images arejoined together efficiently by using the specified document as the key.

Referring to the flow chart of FIG. 3, an explanation will be given ofthe sequence of processes that are carried out in the joining operation.

Firstly, when a joining mode is selected through an operation panel, notshown (S1), a specified document that has been preliminarily selected isscanned (S2). The partial document data read through the CCD sensor 6are stored in the image memory 43 (S3) after having been subjected tothe predetermined processing. Successively, the rest of the documentsother than the specified document are scanned (S4), and the partialdocument data read through the CCD sensor 6 are stored in the imagememory 43 after having been subjected to the predetermined processing(S5).

These scanning process for the documents and storing process for thepartial document data (S4 and S5) are repeated until a judgement is madeat S6 that the reading operation of the documents has been completed. Inthis manner, information for discriminating the partial document data ofthe specified document from those of the other documents is inputted bystoring the specified document data of the specified document at thebeginning.

After completion of the reading of the documents, when a joiningoperation is instructed (S7), features on the specified document areextracted by retrieving data corresponding to predetermined lines fromthe edge of the partial document data of the specified document andrecognizing particular lines and characters within the retrieving regionin the joint recognition section 44 (S8). Further, in the same manner,features are extracted from the rest of the documents that were readafter the specified document (S9). Then, the features extracted from therest of the partial document data are compared with the featuresextracted from the partial document data of the specified document, andif there is a portion where those features coincide with each other, itis judged that a coincidence of data is found between joints of thespecified document and the rest of the documents (S10). Successively,the data arranging section 45 arranges the corresponding partialdocument data so that the edges of the partial document data forming thecoincident joints are aligned side by side with each other (S11).

Next, in the positioning section 46, a check is made to find thecoincidence of data by shifting the other partial document data in themain scanning direction or in the sub scanning direction that isorthogonal to the main scanning direction while maintaining thespecified document data in a fixed state. Thus, the positioning iscarried out so that both of the data are set at a position where imagesbetween the joints are connected most smoothly (S12). Thereafter, in thecombination-processing section 47, the partial document data thuspositioned are combined together. Additionally, upon carrying out theabove feature-extracting operation, if there is a side having no imagedata among the edge portions of the partial document data, this side isassumed to form an edge in an image after completion of the joiningoperation. Then, the rest of sides are successively positioned inrelation to the other partial document data.

After completion of the positioning, a judgement is made as to whetherall the data processing has been completed (S13). If all the dataprocessing have not been completed, a judgement is made as to whether ornot image data forming joints exist at the sides other than the sidethat has been assumed to be an edge of an image as to the unprocessedpartial document data (S14). If no joints exist at the sides other thanthe side corresponding to an edge of an image, the judgement is made as"YES" at S14, and a warning display indicating "NO" is given to informthat no joining process is operable (S15), thereby stopping theoperation.

In contrast, if joints exist at the sides other than the sidecorresponding to an edge of an image, the judgement is made as "NO" atS14, and the sequence proceeds to S9. Then, the extracted features arecompared between the partial document data that are positioned inrelation to the specified document data and the unprocessed partialdocument data, and comparison, rearrangement and positioning of data arecarried out at the joints (S10 to S12).

If it is determined at S13 that all the processing has been completed, ajudgement is made as to whether or not the size of copy sheets whereonthe joined image is formed is specified (S16). If the size of the copysheets is not specified, the judgement is made as "NO" at S16, therebyselecting copy sheets having the largest size among the copy sheets thatare set in the digital copying machine (S17), and a variablemagnification operation is carried out on the combined document data inaccordance with the copy sheets having the largest size (S18). Incontrast, if the size of the copy sheets is specified, the judgement ismade as "YES" at S16, and the variable magnification operation iscarried out on the combined document data in accordance with the size ofcopy sheets that has been specified (S18). Further, conversion of thecoordinates is executed on the document data according to thelongitudinal feeding or the lateral feeding of the copy sheets, ifnecessary, and the subsequent data are released to the laser driver unit7, thereby copying the combined image on copy sheets (S19).

Here, in the above processing, if a loss of image occurs at the jointsof the partial document data, a compensating operation for the loss ofimage is carried out. That is, when the partial document data arepositioned, the positioning is made while taking account of such a lossof image, and an additional image to compensate for the loss of image isformed in accordance with the image data that form the joints.

Next, an explanation will be given on the above-mentioned joiningoperation more specifically by reference to FIG. 4 as well as FIGS.5(a), 5(b) and 5(c). Here, suppose that nine partial document data 58athrough 58i, for example shown in FIG. 4, are stored in the image memory43, and that the partial document data 58a is preliminarily determinedas a specified document that forms the center of an image. The joiningoperation between the partial document data 58a and the partial documentdata 58b is carried out following the sequence as shown in FIGS. 5(a),5(b) and 5(c).

More specifically, data corresponding to predetermined lines from theends of the respective partial document data 58a and 58b (indicated byregions having slanting lines in FIG. 5(a)) are retrieved so as torecognize peculiar lines and characters. Here, in the case whencoincidence of the data is recognized as shown by the broken lines, withone of the partial document data 58a maintained in a fixed state, thebest-suited position where the portions of the image are suitably joinedtogether is found by checking the consistency of the data while shiftingthe other partial document data 58b in the main scanning direction or inthe sub scanning direction, as is indicated by alternate long and twoshort dashes lines in FIG. 5(b). In this manner, the positioning of thepartial document data 58a and 58b is carried out.

Likewise, the positioning is carried out as to the other sides of thepartial document data 58a, that is, the specified document, by using thepartial document data 58d, 58f and 58h (see FIG. 4) that containcoincident data at the respective joints. In contrast, as to the partialdocument data 58c, 58e, 58g and 58i that have no adjacent sides to thepartial document data 58a, comparison of data is carried out withrespect to the partial document data 58b, 58d, 58f and 58h that havealready been positioned in relation to the partial document data 58a,and the arrangement, positioning, etc. of the partial document data arecarried out in accordance with the coincident data.

In this manner, the positioning of the partial document data 58a through58i is carried out, and after combining the images, the joined documentdata are subjected to a variable magnification operation to be formedinto a desired size, thereby obtaining a reduced copy 59 as shown inFIG. 5(c).

As described above, in the case where a plurality of documents aresuccessively read, the digital copying machine of the present embodimentextracts features from the respective documents, and forms one imagefrom those documents by joining the documents with respect to sideswhereon coincidence of data is found in the features.

Therefore, the present invention eliminates troublesome and timeconsuming tasks such as reducing a plurality of documents respectively,and trimming and sticking together the reduced portions to form onedocument, which was necessary in the conventional arrangement. Further,it becomes possible to prevent offsets that would have occured at thejoints of the combined document due to errors in reduction rate.Moreover, since it is no longer necessary to repeatedly make copies,wasteful use of toner, copy sheets, etc. can be prevented.

Furthermore, in the digital copying machine of the present embodiment,the joined image is variably magnified into a desired size. Thus, thisarrangement makes it unnecessary for the user to calculate a reductionrate in accordance with the number of documents and the size of copysheets whereon the image is formed.

In the case of joining partial images of a number of documents, iffeatures extracted from the respective documents are compared with oneanother at random, it will take a lot of time to search for sides havingcoincident data. However, in the digital copying machine of the presentembodiment, an image that has been first read is recognized as aspecified document as described earlier, and the joining operation iscarried out based on the specified document. Therefore, even in the caseof using a number of documents, since one document which contains themost outstanding features or which forms the center of image is firstread as the specified document in the the digital copying machine, thedetection on joints is carried out in a short time, and the joints canbe joined each other accurately.

[EMBODIMENT 2]

Referring to FIGS. 1 and 2 as well as FIGS. 6 and 7, the followingdescription will discuss another embodiment of the present invention.Here, for convenience of explanation, those members that have the samefunctions and that are described in the aforementioned embodiments areindicated by the same reference numerals and the description thereof isomitted.

As with the digital copying machine described in embodiment 1, a digitalcopying machine of the present embodiment has a structure shown in FIG.2. Further, the digital copying machine is provided with an imageprocessing section, which has a construction as shown in FIG. 1.

In the digital copying machine of the present embodiment, the layout ofpartial document data forming one image is determined in a right andleft direction as well as in an up and down direction by setting thedivided state of the image in a predetermined manner. The divided stateof the image is determined by, for example, the number of rows to dividethe documents and the number of documents that are contained in one row.The digital copying machine determines the layout of the partialdocument data in the order of storage made by the image memory 43 inaccordance with the number of rows to divide the documents and thenumber of documents contained in one row that have been predeterminatelyset, and the adjacent partial document data are joined togetheraccording to the layout.

Referring to the flow chart of FIG. 6, the sequence of processes thatare carried out during a joining operation in the digital copyingmachine of the present embodiment.

Firstly, a joining mode is selected through an operation panel, notshown, (S21), and the number of documents contained in one row and thenumber of rows are successively determined (S22). Then, documents havingdivided images are successively scanned in the order by which thejoining operation is carried out (S23), and data read through the CCDsensor 6 are stored in the image memory 43 (S24). In accordance with thenumber of documents contained in one row and the number of rows that arepreliminarily set, the partial document data thus stored in the imagememory 43 are determined in their layout in the order they are inputted.When the joining operation is instructed (S25), features on thedocuments are extracted by retrieving data corresponding topredetermined lines from the edge of the partial document data so as torecognize peculiar lines and characters, thus carrying out afeature-extracting operation on the partial document data (S26).

Then, in accordance with the layout of the partial document datadetermined by the order of storage made by the image memory 43, a checkis made to see if the data forming joints coincide with each other bycomparing the features preliminarily extracted between the adjacentpartial document data (S27). If it is determined that the data coincidewith each other, positioning is made so as to get the joints connectedto each other smoothly by shifting one partial document data with theother partial document data maintained in a fixed state (S29).

These judgement on the coincidence of data and positioning of thepartial document data are first made between the partial document datafirstly read and the partial document data secondly read. Successively,positioning is carried out between the partial document data secondlyread and those thirdly read, and then between the partial document datathirdly read and those fourthly read, and so on. When the positioninghas been made with respect to all the documents contained in one row, itis determined that the joining operation has been completed with respectto the partial document data forming the first row, and a joiningoperation is started with respect to the partial document data formingthe second row.

As to the joining operation on the partial document data forming thesecond row, it is necessary to take account of not only the lateralconnection of the image but also the longitudinal connection thereof,that is, the connection to the partial document data forming the firstrow. Therefore, as to the partial document data to be disposed in thesecond row and the following rows, the positioning is successively madewhile paying attention to coincidence of data in the lateral andlongitudinal joints.

In contrast, if it is determined at S27 that no coincidence is foundbetween the data at the joints, and a warning display indicating that nojoining process is operable (S28), thereby stopping the operation.

Further, when the positioning has been completed on all the partialdocument data stored in the image memory 43 such that the partialdocument data have been combined together, a judgement is made as towhether or not the size of copy sheets whereon the joined image isformed is specified (S30). If the size of the copy sheets is notspecified, copy sheets having the largest size among the copy sheetsthat are set in the digital copying machine are automatically selected(S31), and a variable magnification operation is carried out on thecombined document data in accordance with the copy sheets having thelargest size (S32). In contrast, if the size of the copy sheets isspecified, the judgement is made as "YES" at S30, and the variablemagnification operation is carried out on the combined document data inaccordance with the size of copy sheets that has been specified (S32).

After having been subjected to the variable magnification operation inaccordance with the size of the copy sheets, the document data arefurther subjected to conversion of the coordinates in accordance withthe longitudinal feeding or the lateral feeding of the copy sheets, andother predetermined operations. Then, the subsequent data are releasedto the laser driver unit 7, and a predetermined copying operation iscarried out (S33). Here, if the digital copying machine has a functionfor compensating for loss of image, it is possible to compensate for anyloss of image which would occur at the joints of the partial documentdata during the above-mentioned joining operation.

Next, referring to an example wherein one image is formed by joiningtogether eight pages of partial document data 61a through 61h (where thenumber of documents forming one row is four and the number of rows istwo) as shown in FIG. 7(a), an explanation will be given in detail onthe above-mentioned operation.

First, the divided state of image (in this case, the number of documentsforming one row is four and the number of rows is two) is entered, andthe partial document data 61a through 61h are then stored in the imagememory 43 in succession. Thus, the partial document data 61a through 61hare disposed in two rows in a divided manner according to the order ofstorage made by the image memory 43.

First, the data-retrieving operation, the positioning, etc. are carriedout with respect to the partial document data 61a through 61d formingthe first row. More specifically, if coincidence of data is found at thejoints, the partial document data 61b are positioned in relation to thepartial document data 61a. Likewise, the partial document data 61c arepositioned in relation to the partial document data 61b, and the partialdocument data 61d are positioned in relation to the partial documentdata 61c.

Next, the data-retrieving operation, the positioning, etc. are carriedout with respect to the partial document data 61e through 61h formingthe second row. The partial document data 61e, which are first readamong the partial document data forming the second row, are positionedunder the lower edge of the partial document data 61a in the first rowbased on the data of the upper edge thereof. Then, the partial documentdata 61f are positioned in relation to the partial document data 61b and61e. Likewise, the partial document data 61g are positioned in relationto the partial document data 61c and 61f, and the partial document data61h are positioned in relation to the partial document data 61d and 61g.

The document data, which have been positioned and combined as describedabove, are subjected to a variable magnification operation, conversionof the coordinates, and other operations, and a predetermined copyingoperation is carried out, thereby producing a reduced copy 62 as shownin FIG. 7(c).

As described above, in the digital copying machine of the presentembodiment, the divided state of image is preliminarily set by enteringthe number of rows and the number of documents contained in one row.Further, the layout of the stored partial document data is determined inaccordance with the divided state thus set and the order of the partialdocument data that have been stored in the image memory. Then, thejoining operation is successively executed beginning with the partialdocument data situated on the left end in the first row toward theadjacent partial document data on the right side. After completion ofthe joining operation in the first row, the same operation is carriedout on the second row, thereby finally combining those partial documentdata into an image on one sheet.

Therefore, as with the aforementioned embodiment 1, in the case ofjoining together images read in a divided manner and recording thecombined image on one sheet of paper having a desired size, thearrangement of the present embodiment eliminates troublesome and timeconsuming tasks such as trimming and pasting the divided images andcalculations on reduction rate, thereby improving efficiency of theoperation. Moreover, since it is no longer necessary to repeatedly makecopies, wasteful use of toner, copy sheets, etc. can be prevented.Furthermore, even in the case of using a number of inputted partialdocument data from an image that is divided into many portions, it ispossible to carry out the joining operation without the necessity ofexcessive time, and to ensure high quality in the images by eliminatingoffsets that would occur at the joints.

[EMBODIMENT 3]

Referring to FIGS. 1 and 2 as well as FIGS. 8 through 10, the followingdescription will discuss another embodiment of the present invention.Here, for convenience of explanation, those members that have the samefunctions and that are described in the aforementioned embodiments areindicated by the same reference numerals and the description thereof isomitted.

As with the digital copying machine described in the aforementionedembodiment 1, a digital copying machine of the present embodiment has astructure shown in FIG. 2. Further, the digital copying machine isprovided with an image processing section, which has a construction asshown in FIG. 1.

In the digital copying machine of the present embodiment, marks arepreliminarily put on documents, and the joining operation is carried outin accordance with those marks. The marks are directly put on thedocuments by the use of a pen having a specified color, for example,before the images are read by the CCD sensor 6. More specifically, thedocuments are disposed by assuming the joined state of the images, andfor example, arrows or the like for use as the marks are put on thesides that form joints. The digital copying machine of the presentembodiment has a function for detecting such marks, and retrieves themarks before performing the feature-extracting operation on the partialdocument data.

The sequence of operations for joining these images by the use of themarks indicating the joints will be described below by reference to theflow chart of FIG. 8.

When the joining mode is selected through an operation panel, not shown,(S41), documents whereon the marks are put are scanned (S42), and thepartial document data read by the CCD sensor 6 are stored in the imagememory 43 (S43). Here, as to the order of reading the partial documentdata, it may be determined at random irrespective of the layout of thepartial document data. When all the partial document data are stored inthe image memory 43, the marks that have been put in a specified colorto indicate the joints are retrieved (S44), and a judgement is made asto the presence or absence of the marks (S45). Here, if the marks arenot detected, the judgement is made as "NO" at S45, and a warningdisplay is given to inform that no joining process is operable (S48),thereby stopping the operation.

In contrast, if the marks are detected, the judgement is made as "YES"at S45, and features, that is, peculiar lines and characters, areextracted from the partial document data by retrieving datacorresponding to predetermined lines from the sides at which the markscoincide with each other (S46). Then, a judgement is made as to thepresence or absence of the joints at which the data coincide with eachother by comparing the extracted features (S47). Here, if the joints atwhich the data coincide with each other are not detected, the judgementis made as "NO" at S47, and a warning display is given to inform that nojoining process is operable (S48), thereby stopping the operation.

In contrast, if such joints are detected, the judgement is made as "YES"at S48, and the partial document data are arranged so that the sidesforming the joints in question, that is, the sides whereon the marks areput, are placed side by side with each other (S49). In such a state, thepositioning of the partial document data is executed by finding out thebest-suited position on the joints while shifting one partial documentdata in the main scanning direction or in the sub scanning direction,with the other partial document data maintained in a fixed state (S50).Thereafter, the partial document data are combined together based on theresults of the positioning. Here, the marks still exist on the combineddocument data. However, since the marks are put in the specified color,they are recognized after combining the document data, and erased by thespecified-color omitting process.

After the erasing process of the marks, a judgement is made as towhether or not the size of copy sheets is specified (S51). If the sizeof the copy sheets is not specified, copy sheets having the largest sizeare selected among the copy sheets that are set in the digital copyingmachine (S52), and a variable magnification operation is carried out onthe combined document data in accordance with the copy sheets having thelargest size (S53). In contrast, if the size of the copy sheets isspecified, the variable magnification operation is carried out on thecombined document data in accordance with the specified size of copysheets (S53).

After having been subjected to the variable magnification operation inaccordance with the size of the copy sheets, the document data arefurther subjected to conversion of the coordinates in accordance withthe longitudinal feeding or the lateral feeding of the copy sheets, andother predetermined operations. Then, the subsequent data are releasedto the laser driver unit 7, and a joined image is copied on a copy sheet(S54). Here, if the digital copying machine has a function forcompensating for losses of image, it is possible to compensate for anyloss of image which would occur at the joints of the partial documentdata.

Next, referring to an example wherein the partial document data 64 and65, for example, shown in FIG. 9(a) are stored in the image memory 43,an explanation will be given in detail on the above-mentioned operation.In the partial document data 64 and 65, a mark 63 is preliminarily putin a specified color with a pen on sides 64a and 65a whereon the joiningoperation is carried out. When the joining operation of the images iscarried out, the mark 63 is first retrieved prior to thefeature-extracting operation on peculiar lines and characters from thepartial document data 64 and 65. In the feature-extracting operationfrom the partial document data 64 and 65, assuming that only the sides64a and 65a having the mark 63 form joints, data corresponding topredetermined lines from the edges of the sides 64a and 65a areretrieved.

As shown in FIG. 9(b), when portions at which the extracted featurescoincide with each other are detected, the best-suited position on thejoints is found by shifting one partial document data 65 in such amanner as indicated by alternate long and two short dashes lines in FIG.9(b) with the other partial document data 64 maintained in a fixedstate. After positioning the partial document data 64 and 65, both ofthe partial document data 64 and 65 are combined together. Thereafter,the mark 63 is erased from the combined document data by thespecified-color omitting process, and the variable magnificationoperation, etc. are carried out on the subsequent document data, therebyproducing a reduced copy 66 as shown in FIG. 9(c).

As described above, in the digital copying machine of the presentinvention, upon executing the joining operation, the marks indicatingjoints are put in a specified color with a pen on documents to bejoined, before the documents are read by the CCD sensor 6. Therefore, aswith the aforementioned embodiment 1, troublesome and time consumingtasks such as trimming and pasting the divided images and calculationson reduction rate are eliminated, thereby improving efficiency of theoperation. Further, since it is no longer necessary to repeatedly makecopies, wasteful use of toner, copy sheets, etc. can be prevented.Moreover, in the digital copying machine, upon retrieving the partialdocument data so as to detect joints, the joints are recognized bydetecting the marks; this makes it possible to shorten the processingtime, and to join the read images together more accurately and quickly.

Additionally, if the number of divisions of an image increases as shownin FIG. 10, marks having different shapes are put on respective sidesforming different joints of the partial document data 67a through 67f.This arrangement makes it possible to detect sides whereon data coincidewith each other between the joints more quickly. Thus, as with theabove-mentioned case, the joining operation of the images is carried outmore accurately and quickly.

[EMBODIMENT 4]

Referring to FIGS. 1 and 2 as well as FIGS. 11 through 14, the followingdescription will discuss still another embodiment of the presentinvention. Here, for convenience of explanation, those members that havethe same functions and that are described in the aforementionedembodiments are indicated by the same reference numerals and thedescription thereof is omitted.

As with the digital copying machine described in the aforementionedembodiment 1, a digital copying machine of the present embodiment has astructure shown in FIG. 2. Further, the digital copying machine isprovided with an image processing section, which has a construction asshown in FIG. 1.

In the digital copying machine of the present embodiment, numbers arepreliminarily put on documents, prior to the reading operation of thedocument data that is performed by the CCD sensor 6, and the joiningoperation is carried out in accordance with those numbers. The numbersare put on the documents to be joined together by the use of a penhaving a specified color before the images are read by the CCD sensor 6.The numbers indicate the order of the joining operation.

The sequence of operations for joining those documents whereon thenumbers indicating the order of the joining operation are put will bedescribed below by reference to the flow chart of FIG.

When the joining mode is selected through an operation panel, not shown,(S61), documents whereon the numbers are put are scanned (S62), and thepartial document data read by the CCD sensor 6 are stored in the imagememory 43 (S63). Here, as to the order of reading the partial documentdata, it does not need to follow the sequence of the joining operation.

After all the partial document data are stored in the image memory 43,the numbers of documents that are disposed in the x-direction andy-direction are determined through the operation panel. Thus, the layoutof the stored partial document data is specified (S64). As shown in FIG.12, for example, suppose that six documents whereon the numbers 1through 6 are put are scanned, and that the number of documents in thex-direction is two and the number of documents in the y-direction isthree. In this case, as shown in FIG. 13, the layout of the partialdocument data is specified so that the numbers are successively put fromleft to right and from up to down in the drawing.

When the layout of the partial document data is specified in thismanner, the numbers put on the respective partial document data storedare recognized (S65). When the joining operation is specified (S66), thepartial document data are rearranged in accordance with the numbers Chathave been put thereon, and the partial document data are disposed at thepositions that have been preliminarily specified (S67). Then,outstanding characters and lines that form features are recognized byretrieving data corresponding to predetermined lines from the edges ofthe partial document data. With this arrangement, the features thusrecognized are compared with each other between the adjacent partialdocument data, and portions at which the data coincide with each otherare detected as joints of an image (S68).

Here, if no joints are detected, the judgement is made as "NO" at S68.Also, if it is determined at S70 that the joining operation has not beencompleted on all the partial document data, a warning display is givento inform that no joining is operable (S71), thereby stopping theoperation.

In contrast, if joints at which the data coincide with each other aredetected, the judgement is made as "YES" at S68, and one partialdocument data is shifted in the main scanning direction or in the subscanning direction with the other partial document data maintained in afixed state in order to find coincidence of the data. Thus, thebest-suited position on the joints is detected and the positioning ofthe partial document data is carried out (S69), thereby permitting thepartial document data to be combined. These operations including thedetection on joints, the positioning, the combining, etc. are carriedout successively in accordance with the numbers put on the partialdocument data and the layout of the partial document data that has beenpreliminarily specified. Additionally, the numbers that have been put inthe specified color are erased by the specified-color omitting processafter combining the document data.

After it is determined at S70 that the joining operation has beencompleted on all the partial document data stored in the image memory43, a judgement is made as to whether or not the size of copy sheets isspecified (S72). If the size of the copy sheets is not specified at S72,copy sheets having the largest size are selected among the copy sheetsthat are set in the digital copying machine (S73). Then, a variablemagnification operation is carried out on the combined document data inaccordance with the copy sheets having the largest size (S74). Incontrast, if the size of the copy sheets is specified, the judgement ismade as "YES" at S72, the variable magnification operation is carriedout on the combined document data in accordance with the specified sizeof copy sheets (S74). After having been subjected to the variablemagnification operation in accordance with the size of the copy sheets,the document data are further subjected to other predeterminedoperations. Then, the subsequent data are released to the laser driverunit 7, and a joined image is copied on a copy sheet (S75).

Additionally, in the above processing, if a loss of image occurs at thejoints, a compensating operation for the loss of image is carried out inthe same manner as the case described in embodiment 1.

Next, referring to an example wherein a joining operation is carried outon six documents shown in FIG. 12, an explanation will be given indetail on the above-mentioned operation. For example, as to the partialdocument data 70 and 71 whereon number 1 and number 2 are respectivelyput as shown in FIG. 14(a), features are extracted by retrieving datacorresponding to predetermined lines from the edges (indicated byslanting lines in the drawing) with respect to the sides placed oppositeto each other.

Then, after comparing the extracted features, if the features coincidewith each other, the portions in question are detected as joints.Thereafter, as shown in FIG. 14(b), the best-suited position on thejoints is found by shifting one partial document data 71 in such amanner as indicated by alternate long and two short dashed lines withthe other partial document data 70 maintained in a fixed state. Afterthis positioning, both of the partial document data 70 and 71 arecombined together. Thereafter, the numbers are erased from the combineddocument data by the specified-color omitting process, and the sameoperations are carried out between the other partial document data,thereby producing a reduced copy 72 as shown in FIG. 14(c).

As described above, in the digital copying machine of the presentembodiment, the joining operation is carried out in accordance with thenumbers put on the documents and the layout of the partial document datathat is specified by the numbers. Therefore, as with the aforementionedembodiment 1, troublesome and time consuming tasks such as trimming andpasting the divided images and calculations on reduction rate areeliminated, thereby improving efficiency of the operation as well asreducing wasteful use of copy sheets, toner, etc. Further, uponretrieving the partial document data so as to detect joints, since thedetecting operation is readily carried out in accordance with thenumbers and the specified layout, it is possible to shorten theprocessing time. Even in the case of using a number of divided documentsforming one image, the stored documents can be joined together quicklyand accurately.

[EMBODIMENT 5]

Referring to FIGS. 1 and 2 as well as FIGS. 15 through 28, the followingdescription will discuss still another embodiment of the presentinvention. Here, for convenience of explanation, those members that havethe same functions and that are described in the aforementionedembodiments are indicated by the same reference numerals and thedescription thereof is omitted.

As with the digital copying machine described in the aforementionedembodiment 1, a digital copying machine of the present embodiment has astructure shown in FIG. 2. Further, the digital copying machine isprovided with an image processing section, which has a construction asshown in FIG. 1.

In the digital copying machine of the present embodiment, specific imagedata forming features are extracted from all the sides of the partialdocument data that have been stored in the image memory 43, and thejoining operation is carried out, beginning with the partial documentdata that include the most specific image data that have been extracted.Referring to the flow chart of FIG. 15, an explanation will be given onthe joining operation that is carried out in accordance with the amountof data.

When the joining mode is selected through an operation panel, not shown,(S81), documents including divided images are scanned (S82), and thepartial document data read by the CCD sensor 6 are stored in the imagememory 43 (S83). These scanning process on the documents and storingprocess on the partial document data (S82 and S83) are repeated as manytimes as the number of the documents forming the image until thecompletion of the reading process is determined at S84.

After the completion of the reading process, when the joining operationis instructed (S85), a retrieving process is conducted on the datacorresponding to predetermined lines from the edges with respect to allthe sides of the partial document data stored. Thus, with respect toeach side of the partial document data, outstanding lines and charactersor the amount of change in data, etc. are recognized as the specificimage data, and features are thus extracted from the respective partialdocument data (S86).

After the features have been extracted from the respective sides of allthe partial document data, the amount of change, etc. in the data of therespective sides that have been extracted as the features are comparedwith one another, thereby comparing the amount of specific image dataforming the features. Then, in accordance with the results of thecomparison, the joining operation is successively carried out beginningwith the sides containing the largest amount of data. In other words, ajudgement is made as to the coincidence of data between the joints inquestion by comparing the extracted features in succession beginningwith the sides containing the largest amount of data (S87). If the datacoincide with each other, the partial document data are rearranged thatthe corresponding ends of the partial document data forming the jointsare placed opposite to each other (S88), and the positioning is made sothat the images are connected to each other smoothly.

The judging process as to the coincidence of data (S87), the rearrangingprocess (S88) and the positioning process on the partial document dataare repeated in accordance with the above-mentioned order until thecompletion of all the data processing is determined at S89. In contrast,if the judgement is "NO" at S87, the rearranging process on the partialdocument data is not carried out, and the sequence proceeds to S89.Here, during the above process, if there are any sides whereon thejoining is not operable, a flag indicating "no coincidence" is set,thereby executing the joining operation on the rest of the sides.

After completion of all the data processing, a compensating operationfor loss of data is conducted on the sides for which the flag of "nocoincidence" has been set (S90). Then, at S91, a judgement is made as towhether or not the compensating operation for loss of data has beencompleted. If the compensating operation has been completed, a judgementis successively made as to whether or not the joining operation has beencompleted (S93). This judgement on the completion of the joiningoperation is made so as to determine whether or not all the documentdata stored are combined into an image on one sheet.

In contrast, if it is determined at S91 or S93 that the compensatingoperation for loss of data has not completed or the joining operationhas not been completed, a warning display is given to inform that nojoining process is operable (S92), thereby stopping the operation.

After determination of the completion of the joining operation at S93, ajudgement is then made as to whether or not the size of copy sheetswhereon the combined image is formed is specified (S94). If the size ofthe copy sheets is not specified, copy sheets having the largest sizeamong the copy sheets that are set in the digital copying machine areselected (S95), and a variable magnification operation is carried out inaccordance with the copy sheets having the largest size (S96).

In contrast, if the size of the copy sheets is specified, a variablemagnification operation is carried out in accordance with the size ofcopy sheets that has been specified (S96). Further, conversion of thecoordinates is executed on the document data according to thelongitudinal feeding or the lateral feeding of the copy sheets (S97),and the subsequent data are released to the laser driver unit 7, therebycarrying out copying operations of the combined image on copy sheets(S98).

Referring to a flow chart in FIG. 16, an explanation will be givenhereinbelow on the extraction of features on the documents in theabove-mentioned joining operation.

Firstly, one side, from which features are extracted, is selected atrandom from the partial document data that have been stored (S101), andan area corresponding to predetermined lines from the end of theselected side, for example, corresponding to several tens of linesinward from the end, is specified as a feature-extraction area (S102).Then, a selection is made to find a best-suited method for making thefeatures clear among methods using the outstanding lines and characters,the arrangement and pattern of data, the amount of change in data, etc.,and features that are present within the feature-extraction area areextracted (S103). The extracted features are digitized and stored(S104).

The selection of sides from which features are extracted (S101), thespecifying process of the area (S102), the feature-extracting process(S103) and the storing process of the features (S104) are repeated withrespect to all the partial document data stored until the completion offeature-extracting process on all the data is determined at S105. Afterthe completion of all the feature-extracting process on all the partialdocument data is determined at S105, comparisons are made between theamounts of data stored in the form of digits concerning the respectivesides, and the order of the joining operations is set in accordance withthe increment amount of data that are present on the respective sides(S106).

In other words, there is a high possibility that a pair of sides havingalmost the same amounts of data forming the features have coincidentimages. Therefore, the sides are successively combined to make pairs inaccordance with the amounts of data that are present on the respectivesides beginning with the sides having the largest amount of data. Then,joints in the partial document data in question are recognized by makinga judgement as to whether or not the data forming the features arecoincident between the paired sides. In this manner, since the joiningoperation is carried out in succession beginning with the sides havingthe most amount of data, the joints can be recognized in a short time incomparison with the case wherein the features of the respective sidesare compared at random. Further, since the layout of the partialdocument data is first determined in a rough manner beginning with thesides having the largest amount of data, it is possible to find sideshaving coincident data easily in a short time even in the case of sideshaving less amount of data, whose joints were not easily found.

Additionally, in the image memory 43, after detecting the size of adocument to be read in accordance with the controlling for the normalimage reading, storing, copying, etc., an address space is provided inthe memory. As shown in FIG. 17, document data are stored therein at arate of one image per page. Therefore, as shown in FIG. 18, each end ofan image (for example, indicated by an area having slanting lines inFIG. 18) can be clearly indicated by an address on the memory, and thefeature-extraction area can be specified in accordance with the address.

After extracting respective features and the comparisons are madebetween the amounts of data forming the features in the manner asdescribed above, a judgement is made as to the coincidence ornon-coincidence of the data beginning with the sides having the largestamount of data forming the features, in accordance with a sequence ofprocesses as shown in the flow chart of FIG. 19.

Firstly, features of a pair of sides to be joined, that is, features ofa pair of sides having almost the same amounts of data, are roughlycompared with each other (S111), and a judgement is made as to whetheror not the features thus compared coincide with each other within arange of a predetermined approximation (S112). If the features almostcoincide with each other, the partial document data are arranged so thatthe corresponding sides are aligned side by side with each other, andpositioning is performed in the image memory 43 so that the arrangement,pattern, etc. of the data are well suited. In other words, the imagesare compensated for their offsets caused when they are read by shiftingone of the images in an up and down direction and in a right and leftdirection (S113 and S115), and also compensated for their tilts causedby the tilts of the documents when they are read by rotating one of theimages by several degrees (S117).

Moreover, if it is determined that no coincidence is found between thefeatures when the features are roughly compared, or when one of theimages is shifted in an up and down direction and in a right and leftdirection, or when one of the images is rotated (S112, S114, S116, andS118), a judgement is again made as to whether or not the featurescoincide with each other within a range of a predetermined approximation(S120) after one of the images is rotated by 180° (S119). If it isdetermined at S120 that no coincidence is found between the featureseven within the range of the predetermined approximation, one of theimages is further rotated by several degrees (S121). Even after theseprocesses, if it is determined that no coincidence is found between thefeatures (S122), a flag indicating "no coincidence" is set (S123).

More specifically, since the documents have a rectangular shape in mostcases, their image might be read upside down in an up and downdirection. Therefore, even if no coincidence is found between the imagesin their stored states, the coincidence is again confirmed in the imagememory 43 by rotating one of the partial document data by 180°. Further,taking account of the case when upon reading, the document is set in aslightly tilted state, even if no coincidence is found between theimages after making the 180° rotation, the features are again comparedby rotating one of the images by several degrees.

In contrast, if it is determined at S120 and S122 that the featurescoincide with each other within the range of the predeterminedapproximation, the corresponding sides are recognized as joints and thesequence proceeds to S113. Then, the shift of the images in an up anddown direction and in a right and left direction, the rotation of theimages, etc. are performed as described earlier so that the arrangement,pattern, etc. of the data are well suited, thus making the positioningof the partial document data.

Next, referring to the flow chart of FIG. 20, an explanation will begiven in detail concerning the judgement on the completion of all thedata processing.

If a plan for the joining operation is preliminarily inputted through acertain method upon reading images or other occasions, it is determinedat S124 that there is an inputted plan. In this case, since the layoutof the partial document data is set by the inputted plan and since thesides merely including the ends of images are preliminarily known, thejoining operation is not carried out on the sides merely including theends of images. Therefore, a judgement is made as to whether or not allthe data processing has been completed (S127), by making a check to seeif the joining operation is being carried out on sides other than thesides merely including the ends of images (S126).

In contrast, if document data are randomly inputted, that is, if no planfor the joining operation is specified, the judgement is made as "NO" atS124. Therefore, a judgement is made as to whether or not all the dataprocessing has been completed (S127), by making a check to see if thejoining operation is being carried out on the four sides in the data(S125). Additionally, in this case where the document data are randomlyinputted, it is determined that the sides on which no coincidence of thefeatures is found are sides merely including the ends of images, and thejoining operation is successively carried out on the other sides.

Here, referring to FIG. 21, an explanation will be given on this indetail. For example, if four images a through d are randomly inputted,judgements as to the coincidence or non-coincidence of the data are madeon the four sides of the respective images a through d. At the time whenall the data processing has been completed on the partial document data,the joining operation has been made on each of the pairs of sides a₄ andb₃, b₂ and d₁, a₂ and c₁, as well as c₄ and d₃ following the orderdetermined by the amounts of the features as described earlier, whileflags for indicating "no coincidence" are set for the other eight sidesmerely including the ends of images (a₁, a₃, b₁, b₄, c₂, c₃, d₂ and d₄).

After completion of all the data processing as described above, if anyflags for indicating "no coincidence" are found at any portions otherthan the ends of images, a compensating operation for the loss of datais carried out. As to the compensating operation for the loss of data,an explanation will be given with reference to the flow chart of FIG.22.

Firstly, a judgement is made as to the presence or absence of the flagsfor indicating "no coincidence" (S131), and if no flags are found, thesequence proceeds to the step for determining the completion of thejoining operation because the compensating operation for the loss ofdata is not necessary. In contrast, if the flags for indicating "nocoincidence" are found, a check is made to see if the joining operationhas been completed on each of the other sides (S132). More specifically,if the joining operation is not applicable due to a certain problem, theflag for indicating "no coincidence" is set. Therefore, in order to makea judgement as to whether the cause of the setting of the flag lies inan error in setting the document, which interrupts the images from beingjoined into one image, or lies in a loss of the image occurred duringthe reading process of the document, a check is made to see if thejoining operation has been completed on each of the other sides.

If it is determined at S133 that the joining operation has not beencompleted on the other sides, it is determined that the setting of theflag is caused by an error in setting the document, and a warningdisplay is given to inform that no joining operation is possible. Incontrast, if it is determined at S133 that the joining operation hasbeen completed on each of the other sides, it is determined that thesetting of the flag is caused by a loss of the image, and a check isinitiated to determine a data-loss area in order to conduct acompensating operation for the loss of data.

In other words, taking account of the joining operation that has beencarried out on the rest of the sides except the side on which the lossof image is supposed to exist, the check is made to determine thedata-loss area assuming that the position of the image having thedata-loss has already been determined in relation to the other images.Firstly, a side to be joined to the side having the data-loss is definedas a first line, and scanning in the sub scanning direction is executedline by line in the main scanning direction until any change appears inthe data (S134). Thus, the data-loss area is determined by defining thefirst line as p as well as defining the line at which a change in thedata has first appeared as q (S135).

For example, in the case where images shown in FIG. 23 are stored in theimage memory 43 as partial document data, partial document data 80containing a loss of data are positioned in relation to adjacent partialdocument data 81 and 82 in accordance with sides 80a and 80b having nodata-loss. Therefore, the position of partial document data 80 is alsodetermined with respect to partial document data 83 which is placedopposite to the loss of data. Thus, the start line for scanning is givenby q (the end of the document data 83) and the line at which a change inthe data has first appeared is indicated by p; therefore, it isdetermined that the data-loss area of the image corresponds to an areabetween the lines p and q.

Next, referring to the flow chart of FIG. 24, an explanation will begiven on the creating operation of compensating data for compensatingfor the data-loss of the images that have been determined as describedabove.

Firstly, the main scanning counter is initialized (S141), and the mainscanning counter counts up to a line where data first appear in the areaon which the above judgement has been made, on one of the partialdocument data (S142). Thus, data, for example, corresponding to severaltens of lines are retrieved, and a check is made to see the tilt, etc.thereof (S143). Successively, a check is made to see if any data of theother partial document data are present in the vicinity of an extendedline from the data that have been confirmed on the tilt thereof (S144).If no data are present, it is determined that no target is identified(S145), a warning display is given to inform that no joining operationis possible.

In contrast, data are present in the vicinity of the extended line, thejudgement is made as "NO" at S145, and compensating data for thedata-loss area are created so as to connect the both of the partialdocument data (S146). The above-mentioned steps (S142 through S146) arecarried out for one line in the main scanning direction. If it isdetermined at S147 that the creation of the data has been completed forall the one line in the main scanning direction, the sequence proceedsto the steps for determining the completion of the joining operation.

Referring to the flow chart of FIG. 25, an explanation will be givenbelow on the decision on the completion of the joining operation. If aplan for the joining operation is preliminarily inputted, it determinedat S148 that there is an inputted plan, and according to the plan, acheck is made to see if all the data are joined together to form oneimage in the manner as instructed (S149). In contrast, if no plan isspecified, a check is made to see if all the data are joined together(S150). Then, if it is determined at S151 that the joining operation hasnot been completed, a warning display is given to inform that nooperation is possible. However if it is determined that the joiningoperation has been completed, the sequence proceeds to the steps forchecking to see if the size of copy sheets has been specified.Thereafter, the aforementioned operations, such as the variablemagnification operation, coordinates-converting operation, are carriedout, thereby copying the combined image.

Next, referring to an example wherein six documents 85 through 90 shownin FIGS. 26(a) through 26(f) are used, an explanation will be given indetail on the joining operation that is carried out in the orderdetermined in accordance with the amounts of data forming features.

Firstly, images on the documents 85 through 90 are successively read,and after the feature-extracting from the respective partial documentdata, the amounts of data that are present on the respective sides arecompared with one another. Based on the results of these comparisons,the order of the joining operation is determined in accordance with theamounts of data that are present on the respective sides. Thus, in theabove case, the joining operation is carried out in the following order:between side A₁ of document 86 and side A₂ of document 89; side B₁ ofdocument 86 and side B₂ of document 87; side C₁ of document 89 and sideC₂ of document 90; side D₁ of document 87 and side D₂ of document 90;side E₁ of document 85 and side E₂ of document 86; side F₁ of document85 and side F₂ of document 88; as well as side G₁ of document 88 andside G₂ of document 89.

To begin with, a judgement is made as to the coincidence ornon-coincidence of data forming the features between side A₁ of document86 and side A₂ of document 89. If the coincidence of the data is found,it is determined that the joining is operable, and the partial documentdata are arranged so that side A₁ and side A₂ are aligned side by sidewith each other. Then, as shown in FIG. 27, the positioning is made soas to get the images connected to each other most smoothly by shiftingone partial document data 89b in the main scanning direction or in thesub scanning direction as indicated by alternate long and two shortdashes lines in FIG. 27 with the other partial document data 86amaintained in a fixed state, in search for the coincidence of data.

This operation is successively carried out on the respective sidesaccording to the order that is determined as described above, and acombined image on one sheet is created by joining together the documents85 through 90 that have been read in a divided manner. Then, thecombined image is subjected to predetermined operations such as avariable magnification operation and a conversion of the coordinates,and the combined partial document data are released to the laser driverunit 7, thereby producing a copy 91 as shown in FIG. 28.

As described above, in the digital copying machine 0f the presentembodiment, when divided images are joined together to form one combinedimage, the joining operation is successively carried out beginning withsides that contain the largest amount of data forming features. If anumber of documents are used or if a complicated image is used, it willtake a lot of time to find out sides whereon the data forming featurescoincide with each other, and the possibility of error will increase.

However, with the arrangement wherein the joining operation is carriedout in succession beginning with sides that contain the largest amountof data, it is possible to shorten time required for recognizing joints,to shorten the processing time to a great extent, and to join imagesmore accurately. Therefore, it becomes possible to improve theefficiency of operation in joining divided images, and to ensure highquality in the images.

[EMBODIMENT 6]

Referring to FIG. 2 as well as FIGS. 29 through 32, the followingdescription will discuss still another embodiment of the presentinvention. Here, for convenience of explanation, those members that havethe same functions and that are described in the aforementionedembodiments are indicated by the same reference numerals and thedescription thereof is omitted.

As with the digital copying machine described in the aforementionedembodiment 1, a digital copying machine of the present embodiment has astructure shown in FIG. 2. Further, the digital copying machine isprovided with an image processing section, which has a construction asshown in FIG. 29. The image processing section has a document-colorrecognition section 95 (document-color recognition means) forrecognizing colors of a document read by the CCD sensor 6. Here, exceptfor the document-color recognition section 95, the construction of theimage processing section is the same as that of the image processingsection (see FIG. 1) that is provided in the digital copying machine ofthe aforementioned embodiment 1.

Partial document data read by the CCD sensor 6 are inputted to the imagememory 43 through the R, G, B level adjusting section 40, the A/Dconvertor 41, and the shading correction section 42. Also, the partialdocument data are inputted from the CCD sensor 6 to the document-colorrecognition section 95 where the colors of the document are respectivelyrecognized. The subsequent color data obtained from the document-colorrecognition section 95 are inputted to the joint recognition section 44in the joint processing section 48 whereto the partial document datafrom the image memory 43 are inputted.

In this arrangement, when the joint mode is instructed, a plurality ofdocuments are successively scanned, and partial images of the respectivedocuments are read as respective partial document data and subjected topredetermined processing. Thereafter, the partial document data aretemporarily stored in the image memory 43, and further sent to the jointrecognition section 44. The joint recognition section 44 retrieves datacorresponding to predetermined lines from the edges of the partialdocument,data while comparing the color data from the document-colorrecognition section 95 with the respective partial document data.Through the retrieving process, the joint recognition section 44recognizes the arrangements of colors in the vicinity of the edges ofthe image, thereby recognizing as joints a pair of sides whereon thearrangements of colors coincide with each other between the edges of theimage.

After recognizing the joints in accordance with the colors of thepartial document data, the various operations such as rearranging,positioning, combining and variable magnification operations aresuccessively carried out, and the images that have been read in adivided manner are joined together to form a combined image on onesheet.

For example, referring to documents 92 and 93 as shown in FIGS. 30(a)and 30(b), an explanation will be given in detail on the joiningoperation which is carried out in accordance with the colors of thedocuments, as described above. After documents 92 and 93 have beensuccessively scanned and the partial images of those documents have beenread as partial document data, joints are recognized by determiningwhether or not the arrangements of colors on the documents are almostthe same. Here, in the drawings, the difference of colors on thedocuments is indicated by the directions of hatching. Therefore, it isdetected that the color of the upper portion of side H₁ in document 93is the same as that of the upper portion of side H₂ in document 92.Also, it is detected that the color of the lower portion of side H₁ indocument 93 is the same as that of the lower portion of side H₂ indocument 92. Thus, it is recognized that these sides H₁ and H₂ can bejoined together.

As illustrated in FIG. 31, after coincidence of the arrangements ofcolors on sides H₁ and H₂ is determined, the positioning is made in theimage memory 43 so that the color data coincide with each other byshifting one partial document data 92a in the main scanning direction orin the sub scanning direction, as is indicated by alternate long and twoshort dashes lines in the drawing, with the other partial document data93a maintained in a fixed state. Thereafter, the predeterminedoperations are carried out in the same manner as described in theaforementioned embodiment 1, and the variable magnification operation,conversion of the coordinates, etc. are carried out, if necessary. Then,the subsequent combined document data are released to the laser driverunit 7, thereby producing a copy 94 on one sheet as shown in FIG. 32.

As described above, in the digital copying machine in the presentembodiment, the document-color recognition section 95 is provided in theimage processing section, and the joining operation is carried out basedon the color data of documents that have been recognized in thedocument-color recognition section 95. Therefore, even in the case ofusing a number of documents, it is possible to shorten time required forthe operation and to ensure an accurate joining operation by preventingerrors. Thus, it becomes possible to improve the efficiency of theoperation and to enhance the quality of the images.

[EMBODIMENT 7]

Referring to FIG. 2, FIG. 15, and FIG. 21 as well as FIGS. 33 through36, the following description will discuss still another embodiment ofthe present invention. Here, for convenience of explanation, thosemembers that have the same functions and that are described in theaforementioned embodiments are indicated by the same reference numeralsand the description thereof is omitted.

As with the digital copying machine described in the aforementionedembodiment 1, a digital copying machine of the present embodiment has astructure shown in FIG. 2. Further, the digital copying machine isprovided with an image processing section, which has a construction asshown in FIG. 33. The joint-portion processing section 48 in this imageprocessing section has an image-data extracting section 100 that isinstalled between the data-arranging section 45 and the positioningsection 46. The image-data extracting section 100 extracts image datathat lie in a direction orthogonal to the joints of respective partialdocument data. Here, except for the image-data extracting section 100,the construction of the image processing section is the same as that ofthe image processing section (see FIG. 1) that is provided in thedigital copying machine of the aforementioned embodiment 1.

In this image processing section, partial document data, which areinputted to the joint-portion processing section 48 from the imagememory 43, are first sent to the joint recognition section 44. Here,features are extracted from the respective partial document data, andjoints in the documents are recognized based on the extracted features.The partial document data, from which the joints have been recognized,are arranged in the data arranging section 45 so that the joints atwhich the data forming the features coincide with each other are placedside by side with each other. Then, in the image-data extracting section100, image data that lie in a direction orthogonal to the joints areextracted from the partial document data in order to carry out thepositioning. Thereafter, the partial document data are positioned in thepositioning section 46 so that their shapes and images coincide witheach other at the joints, and the subsequent partial document data arecombined together in the combination processing section 47.

Further, if there are shadow data due to shadows on the documents thatappeared upon reading the images at the joints on the partial documentdata that have been stored in the image memory 43, the range of theshadow data is recognized by the combination processing section 47, andthe shadow data is erased. The partial document data that have beensubjected to the processing in the joint-portion processing section 48are again inputted to the image memory 43.

Moreover, as with the digital copying machine of the aforementionedembodiment 5, the digital copying machine of the present embodimentcarries out the joining operation following the sequence of processes asshown in the flow chart of FIG. 15, thereby forming one image by joiningtogether a plurality of documents. However, the digital copying machineof the present invention differs from the digital copying machine of theaforementioned embodiment 5 in that upon positioning the partialdocument data which have been rearranged so that the joints are placedside by side with each other, the image data lying in a directionorthogonal to the joints on the partial document data are extracted.

In the above-mentioned digital copying machine, a quick joiningoperation shown in FIG. 34(c) is available by the use of the jointprocessing section 48, for example, with respect to partial documentdata 101 and 102 having divided images from one image as shown in FIG.34(a).

Referring to an example wherein two partial document data 101 and 102,shown in FIG. 34(a), are stored in the image memory 43 in the digitalcopying machine of the present embodiment, an explanation will be givenhereinbelow on the feature-extracting process of the respective partialdocument data 101 and 102 in accordance with the flow chart of FIG. 35.Firstly, one side of the image is selected from one document firstscanned (S161), and an area corresponding to predetermined lines fromthe end of the selected side, for example, corresponding to several tensof lines inward from the end, is specified as a feature-extraction area(S162). In this area, a selection is made to find a best-suited methodfor making the features clear among methods using the arrangement,pattern, and color tone of the data depending on the image in question,and features are extracted from the side of the image in question(S163). The features thus extracted are digitized and stored (S164).Successively, one side of the image is selected from the other documentsecondly scanned (S165), and the feature-extraction area is specified inthe same manner as the former image (S166), thereby carrying out thefeature-extracting operation on the image (S167).

Here, an explanation will be given on the feature-extracting operationmore specifically. From the periphery of the two partial document data101 and 102, shown in FIG. 34(a), data corresponding to predeterminedlines (indicated by an area enclosed by a broken line in the drawing)are retrieved, and sides 101a and 102a whereon image data present aredetected depending on the presence or absence of image data.

Here, the feature-extraction area which is discussed in the presentinvention is not limited to one place; the place and number of thefeature-extraction area are different depending on the contents of thedocuments in question. In this operation, it is desirable if there arefeature-extraction areas in the central portion and both of the endportions of the side in question. Further, the central portion and bothof the end portions of the side, portions containing images that aredifferent from those of the surrounding portions, and image dataportions having distinct differences in density are preferentiallyextracted as the features.

After the features are extracted from the respective partial documentdata 101 and 102 as described above, the features extracted from both ofthe partial document data 101 and 102 are compared with each other,thereby determining the coincidence or non-coincidence of the data.Here, in the feature-comparing process, features of data correspondingto the rear side of the document first scanned are firstly compared withfeatures of data corresponding to the leading side of the document nextscanned. Then, if those data do not coincide with each other, featuresof data corresponding to the rest of the sides are compared, on demand.

In this operation, assuming it is highly possible that the partialdocument data 101 and 102 are read in a state, for example, as shown inFIG. 34(a), the features are compared beginning with sides which have ahigh possibility of data coincidence. Therefore, even in a casedifferent from the above case using two documents to form one image,that is, in the case using a plurality of documents to form one image byjoining them together, wherein the joining operations have to beconducted on the other sides, the feature-comparing process is readilyconducted on the other sides. This thereby makes it possible to conductthe joining operations more quickly.

After it is determined that the data coincide with each other, thepositioning is carried out on the partial document data 101 and 102.More specifically, as shown in FIG. 34(b), the partial document data 102is shifted in an up and down direction with the partial document data101 maintained in a fixed state. At this time, as shown in FIG. 36(a)the image-data extracting section 100 extracts image data 103 and 104that lie in a direction orthogonal to the joints of the respectivepartial document data 101 and 102, that is, the seams between the sides101a and 102a as features. Then, the positioning is made on the partialdocument data 101 and 102 based on the image data 103 and 104.

As described above, in comparison with the case where image data 105 and106 that lie in a direction diagonal to the seams of the sides 101a and102a are extracted during the positioning, for example, as shown in FIG.36(b), this case, where the image data 103 and 104 that lie in adirection orthogonal to the seams of the sides 101a and 102a are usedfor the positioning, makes the change of image data clearer. This makesit possible to perform the positioning of the partial document data moreaccurately in a short time.

Next, the positioning is made by shifting the partial document data 102in a right and left direction with the partial document data 101maintained in a fixed state based on the image data 103 and 104 formingthe features. Here, if the image data 105 and 106 in the diagonaldirection have been extracted, the shift in the right and left directionwill again cause offsets in an up and down direction. This results in aproblem that the positioning has to be conducted repeatedly.

In the present embodiment, since the image data 103 and 104 that lie ina direction orthogonal to the joints are extracted for use in thepositioning, the position in the up and down direction remains unchangedeven if the shift is made in the right and left direction. Therefore,with this arrangement wherein the image data 103 and 104 that lie in adirection orthogonal to the joints are extracted as the features, whenthe positioning of the partial document data is made in a right and leftdirection, it is possible to make the positioning only at one time.Thus, it becomes possible to perform the positioning of the partialdocument data 101 and 102 more accurately in a short time. Thereafter,the partial document data 101 and 102 having been subjected to thepositioning are jointed together to form a combined document data 107 asshown in FIG. 34(d) through the processes that are carried out in theimage processing section 47.

Additionally, during the above-mentioned combining operation of thepartial document data 101 and 102, the shape of documents and thefeatures of images are extracted by recognizing lines, characters andimage data, as described earlier. Therefore, based on these data, dataother than the data indicating the shape of documents and the featuresof images, that is, data other than the data of the lines, charactersand images, are erased through the processes in the image processingsection 47 as shadow data produced by the edges of the documents. Thus,shadows that would appear at the joints of the documents are erased.

Next, a judgement is made as to whether or not the data processing ofall the partial document data stored in the image memory 43 has beencompleted. Here, if no plan for the joining operation is specified, thatis, if partial document data are randomly inputted, a check is made tosee if the joining operation is being carried out on the four sides inthe partial document data. Additionally, in this case where the documentdata are randomly inputted, it is determined that the sides on which nocoincidence of the features is found are sides merely forming the endsof images, and the joining operation is successively carried out on theother sides.

Here, referring to FIG. 21, an explanation will be given on this indetail. For example, if four images a through d are randomly inputted asdocument data, judgements as to the coincidence or non-coincidence ofthe data are made twelve times in the total number: [4 (sheets)×4(times)-4 (sides, where the coincidence is found)=12]. As a result, thejoining operation is carried out on each of the pairs of sides a₄ andb₃, b₂ and d₁, a₂ and c₁, as well as c₄ and d₃, while flags forindicating "no coincidence" are set for the other eight sides merelyincluding the ends of images (a₁, a₃, b₁, b₄, c₂, c₃, d₂ and d₄).

After completion of all the data processing as described above, if anyflags indicating "no coincidence" are found at any portions other thanthe ends of images, a compensating operation for the loss of data iscarried out. After completion of the compensating operation, if it isdetermined that the joining operation has been completed, thepredetermined variable magnification operation, conversion of thecoordinates, copying operation, etc. are carried out.

As described above, in the digital copying machine of the presentembodiment, the images on the partial documents are read by the scannerunit 22, and stored in the image memory 43 individually as the partialdocument data 101 and 102. In the joint-portion processing section 48,joints are recognized from the partial document data 101 and 102 storedin the image memory 43, and the positioning section 46 positions thepartial document data 101 and 102 by shifting both of the data in aparallel and vertical direction with respect to the joints so that thepartial documents are joined together.

Further, upon positioning the partial document data 101 and 102, theimage-data extracting section 100 extracts the image data 103 and 104that lie in a direction orthogonal to the joints of the respectivepartial document data 101 and 102. Therefore, the positioning is made sothat the image data 103 and 104 in the orthogonal direction-coincidewith each other. In comparison with the case where the image data 105and 106 that have a slant angle with respect to the joints are extractedduring the positioning, and used for the positioning by shifting them ina parallel and vertical direction, this arrangement makes the change ofdata clearer during the positioning.

Therefore, since the positioning of the partial document data 101 and102 is carried out more effectively by the use of less image data, itbecomes possible not only to accurately join together the documents readin a divided manner without causing any adverse effects on itsefficiency, but also to shorten the time of the joining operation byreducing the amount of information.

[EMBODIMENT 8]

Referring to FIGS. 2, 15, 37, and 38, the following description willdiscuss still another embodiment of the present invention. Here, forconvenience of explanation, those members that have the same functionsand that are described in the aforementioned embodiments are indicatedby the same reference numerals and the description thereof is omitted.

As with the digital copying machine described in the aforementionedembodiment 1, a digital copying machine of the present embodiment has astructure shown in FIG. 2. Further, the digital copying machine isprovided with an image processing section, which has a construction asshown in FIG. 37. The joint-portion processing section 48 in this imageprocessing section has a mono-color conversion section 110 that isinstalled between the data-arranging section 45 and the positioningsection 46. The mono-color conversion section 110 converts colordocument data of R, G, B into mono-color document data. Further, in theimage processing section, the black-document detection section 50 has afunction as a black-document discrimination means, which makes adiscrimination as to whether the partial document data stored in theimage memory 43 are mono-color document data or color document data.Here, except for the mono-color conversion section 110, the constructionof the image processing section is the same as that of the imageprocessing section (see FIG. 1) that is provided in the digital copyingmachine of the aforementioned embodiment 1.

Moreover, as with the digital copying machine of the aforementionedembodiment 5, the digital copying machine of the present embodimentforms one combined image from a plurality of documents by carrying out ajoining operation in accordance with the sequence shown by the flowchart of FIG. 15. However, the digital copying machine of the presentembodiment is different from that of the aforementioned embodiment 5 inthat the joint-portion processing section 48 carries out the positioningon the partial document data based on the mono-color document data thatare obtained by converting the color document data in the mono-colorconversion section 110.

Upon positioning the partial document data, the black-document detectionsection 50 first makes a discrimination as to whether the partialdocument data in question stored in the image memory 43 are mono-colordocument data or color document data. If the discrimination is made inthe black-document detection section 50 that the data in question arecolor document data, the mono-color conversion section 110 in thejoint-portion processing section 48 converts the color document datainto mono-color document data. The mono-color document data thusconverted are stored in the image memory 43.

In the aforementioned embodiments, features are extracted from each ofthe color document data, R, G, B, as shown in FIG. 38(a), and thejudgement is made as to the coincidence or non-coincidence of the databy comparing those features. For this reason, as the amount of dataincreases, the processing time of the joining operation increases.

However, as illustrated in FIG. 38(b), in the joint-portion processingsection 48 of the present embodiment, which is provided with themono-color conversion section 110, the color document data, R, G, areconverted into mono-color document data B_(K) by the mono-colorconversion section 110. Therefore, it is possible to make the judgementas to the coincidence or non-coincidence of the data by using only themono-color document data.

Therefore, since the positioning of the partial document data is carriedout more effectively by the use of less image data, it becomes possiblenot only to accurately join together the documents read in a dividedmanner without causing any adverse effects on its efficiency, but alsoto shorten the time of the joining operation by reducing the amount ofinformation.

[EMBODIMENT 9]

Referring to FIGS. 2, 15, and 34 as well as FIGS. 39 through 42, thefollowing description will discuss still another embodiment of thepresent invention. Here, for convenience of explanation, those membersthat have the same functions and that are described in theaforementioned embodiments are indicated by the same reference numeralsand the description thereof is omitted.

As with the digital copying machine described in the aforementionedembodiment 1, a digital copying machine of the present embodiment has astructure shown in FIG. 2. Further, the digital copying machine isprovided with an image processing section, which has a construction asshown in FIG. 39. The joint-portion processing section 48 in this imageprocessing section has an image enhancing section 111 which is installedbetween the data-arranging section 45 and the positioning section 46.The image enhancing section 111 carries out a compensating operation foredges on image data that exist at joints in the partial document data.Here, except for the image enhancing section 111, the construction ofthe image processing section is the same as that of the image processingsection (see FIG. 1) that is provided in the digital copying machine ofthe aforementioned embodiment 1.

Moreover, as with the digital copying machine of the aforementionedembodiment 5, the digital copying machine of the present embodimentforms one combined image from a plurality of documents by carrying out ajoining operation in accordance with the sequence shown by the flowchart of FIG. 15. However, the digital copying machine of the presentembodiment, to which the image enhancing section 111 is added, makes itpossible to form good images even in the case of conducting a joiningoperation on original half-tone documents such as photographs.

In other words, partial document data that have been read are subjectedto the shading correction and the diffused-portion correction in theshading correction section 42. Therefore, in the case of using originalhalf-tone documents such as photographs, the density distribution ofimages on the partial document data after the corrections is shown inFIG. 40(a). In FIG. 40(a), since a portion of the waveform correspondingto an edge 112 on the image forms a gentle slope, the position of theedge 112 is indistinct. Therefore, if a joining operation is carried outin this condition, the positioning of the partial document data is notconducted appropriately. Further, in the case of conducting the joiningoperation accurately by using analog density values with this sloperemaining unsolved, since it is necessary to provide predeterminedcalculating processes, the processing time will be prolonged.

Therefore, in order to solve this problem, the image enhancing section111 further emphasizes the edge-emphasizing operation that has beengiven by the normal data correction, and as shown in FIG. 40(b),increases the degree of slope of the edge 112 to an extent where theedge 112, which corresponds to a changing point in data, is subject tounder shoot or over shoot. Thus, since it is possible to make the edge112 of the image clearer and to conduct the positioning within anappropriate range of densities, the positioning can be performed moreaccurately and the processing time can be shortened.

An explanation will be given below in detail on the effects of such anedge-emphasizing operation that is provided by the image enhancingsection 111. When an area S (enclosed by an alternate long and shortdashes line) within the side 101a on the partial document data 101, forexample, shown in FIG. 34(a), is enlarged, the state of change indensity at the area S is shown in FIG. 41(a). At the edge 112, since thedensity changes in a moderate fashion, the image is formed in a diffusedstate. Therefore, supposing that the error during reading at a point ina certain density level (the dispersion due to noise, etc.) is Δv, thearea on the partial document data wherein the density of image lieswithin Δv is given by Δl₁. In other words, in the edge 112, thedispersion of position caused on the image is Δl₁ with respect to theerror during reading of Δv.

However, after the image enhancing section 111 has conducted theedge-emphasizing operation on the edge 112, the dispersion of positioncaused on the image becomes Δl₂ with respect to the error during readingof Δv, as shown in FIG. 41(b). Therefore, the dispersion of positioncaused on the image can be reduced with respect to Δv by the use of theedge-emphasizing operation. As a result, it is possible to reduce thediffused portion on the image. Therefore, as shown in FIG. 34(c), thepositioning is performed more accurately in a short time.

Moreover, as another method for enhancing image on the edge 112, adifferential operation may be adopted in the image enhancing section111.

More specifically, when the differential operation is conducted on theedge 112, one raised portion 113 is formed as shown in FIG. 40(c).Therefore, as shown in FIG. 42, outline data 118 and 119 are formed fromthe image data 116 and 117 of the partial document data 114 and 115 bydetecting the raised portion 113. Since it is possible to make the edgesof image clearer by the use of these outline data 118 and 119, thepositioning is performed within an appropriate range of densities.Consequently, the positioning can be performed more accurately on thepartial document data 114 and 115, and the processing time can beshortened.

This operation will be explained hereinbelow more specifically. The areaS shown in FIG. 34(a), that is, the edge 112 shown in FIG. 41(a), issubjected to the differential operation in the image enhancing section111, thereby forming an outline as shown in FIG. 41(c). That is, thedispersion of position caused on the image becomes Δl₃ with respect tothe error during reading of Δv, as shown in FIG. 41(c). Therefore, thedispersion of position caused on the image can be reduced with respectto Δv, and it becomes possible to reduce the diffused portion on theimage. This arrangement makes it possible to distinguish border portionsthat lie between the presence and absence of image data, and a combinedimage, as shown in FIG. 34(c), can be obtained more accurately throughthe positioning for a short time.

In the digital copying machine of the present embodiment, uponpositioning image data of half-tone images such as photographs, theimage enhancing section 111, which is installed in the joint-portionprocessing section, conducts image enhancing operations, such as anedge-density enhancing operation and an out-line data formation by theuse of the differential operation, on image data that lie in thevicinity of joints. As a result, it becomes possible to make borders ofimage data clearer, and the positioning is carried out more accurately.

Therefore, since the positioning of the partial document data is carriedout more effectively by the use of less image data, it becomes possiblenot only to accurately join together the documents read in a dividedmanner without causing any adverse effects on its efficiency, but alsoto shorten the time of the joining operation by reducing the amount ofinformation.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A method for joining together a plurality ofpartial document data in an image processing apparatus, comprising thesteps of:reading a plurality of partial images in succession; storingeach of the read partial images as respective partial document data in astorage device; obtaining specific image data containing features fromthe partial document data by retrieving the partial document data storedin the storage device; selecting a pair of partial document data, anorder of selection being determined by an amount of specific image data,such that partial document data containing a relatively largest amountof specific image data are selected first; comparing the specific imagedata of each of the pair of selected partial document data; recognizingjoints of the pair of partial document data based upon coincidence ofthe specific image data; and positioning the respective partial documentdata in accordance with the recognized joints.
 2. The method of claim 1,wherein the step of selecting a pair of partial document data includesselection of two partial document data containing substantially equalamounts of specific image data.
 3. The method of claim 2, furthercomprising the step of:repeatedly selecting pairs of partial documentdata, each pair including substantially equal amounts of specific imagedata, wherein pairs of partial image data are sequentially selected fromamong the plurality of stored partial image data, wherein partial imagedata containing relatively largest amounts of specific image data aresequentially selected, and repeatedly positioning the respectiveselected partial document data in accordance with the recognized jointsto form an image from the plurality of partial document data.
 4. Animage processing apparatus comprising:input means for reading aplurality of images of a plurality of documents, in succession; storagemeans for storing each of the plurality of images of the plurality ofdocuments as respective partial document data, the plurality ofdocuments being successively scanned by the input means and stored bythe storage means at a time when the image processing apparatus is setinto a joint-portion processing mode, each of the images of theplurality of documents being a partial image of a whole image obtainableby joining the plurality partial images in a non-overlapping manner; andjoint-portion processing means for extracting features, of imagesappearing on edges of the plurality of documents as specific image data,from the partial document data according to a method corresponding tothe images, for selecting partial document data corresponding to a pairof documents among the plurality of documents in an order determined byan amount of specific image data such that a pair of documents includingpartial document data containing a relatively largest amount of specificimage data are selected first, and for joining the selected partialdocument data, wherein the joint-portion processing means repeatedlyperforms selection and joining of the remaining ones of the plurality ofdocuments.
 5. The image processing apparatus of claim 4, wherein thejoint-portion processing means comprises:joint recognition means forrecognizing joints of the partial document data by retrieving theselected partial document data and determining coincidence of thespecific image data of the selected partial document data;data-arranging means for arranging the selected partial document data sothat a pair of the recognized joints are aligned side by side;positioning means for positioning the selected partial document data sothat images at the joints coincide; and combination processing means forcombining the selected partial document data after positioning.
 6. Theimage processing apparatus as defined in claim 5, wherein the jointrecognition means includes a joint recognition section which detectsedge data corresponding to a predetermined area of the partial documentdata by retrieving the partial document data, and which recognizes jointportions by comparing the detected edge data with edge data detectedfrom other partial document data.
 7. The image processing apparatus asdefined in claim 5, wherein the positioning means includes a positioningsection which positions the partial document data to join images on twoof the partial document data together by shifting one of the partialdocument data relative to another partial document data.
 8. The imageprocessing apparatus as defined in claim 5, wherein the positioningmeans includes a positioning section which positions the partialdocument data to join images on two of the partial document datatogether by shifting one of the partial document data relative toanother partial document data in a main scanning direction and in a subscanning direction.
 9. The image processing apparatus as defined inclaim 4, further comprising:variable magnification means for variablymagnifying the joined document data after the joining operation inaccordance with the largest size of a recording medium whereon the imageof the original document is formed.
 10. The image processing apparatusas defined in claim 9, wherein the variable magnification means includesa variable magnification section which, if a size of a recording mediumwhereon an image is formed is not specified, selects a recording mediumof the largest size among recording medium that are prestored in theimage processing apparatus and variably magnifies the joined documentdata after the joining operation in accordance with the size of theselected recording medium.
 11. The image processing apparatus as definedin claim 5,wherein the positioning means comprises a positioning sectionfor, when the joint recognition means recognizes that specific imagedata of partial document data corresponding to the pair of documents donot coincide with each other, rotating partial document datacorresponding to one of the pair of documents by 180 degrees.
 12. Theimage processing apparatus of claim 4, wherein the joint-portionprocessing means includes an image processing section whichdiscriminates a data-loss area of image proximate to a joint portion,caused upon scanning the image through an input means based on apositional relationship of the respective partial document data thathave been set through the positioning, and which forms data forcompensating in the data-loss area in accordance with divided images tobe joined together.
 13. The image processing apparatus of claim 4,wherein the joint portion processing means selects partial document datacorresponding to a pair of documents containing substantially equalamounts of specific image data.
 14. An image processing apparatuscomprising:input means for scanning a plurality of partial images tothereby read an image of an original document that is a composite imageof the plurality of partial images and that is separately unscannable asa whole; storage means for storing the respective plurality of partialimages as respective partial document data, the partial images havingbeen scanned by the input means; and joint-portion processing means forrecognizing reference data in response to an output of the input means,for using the recognized reference data to retrieve joint portions ofthe partial document data stored in the storage means, for using therecognized reference data to recognize the joint portions, and forpositioning the respective partial document data in accordance with therecognized joint portions, wherein the plurality of partial images areon partial documents, the reference data are marks indicating jointportions that have been preliminarily included on the respective partialdocuments and the joint-portion processing means detects the jointportions in accordance with the marks, the marks being a predeterminedcolor and after having joined the partial document data together, thejoint-portion processing means removes the marks from the respectivepartial document data using a predetermined color-omitting operation.15. An image processing apparatus comprising:input means for scanning aplurality of partial images to thereby read an image of an originaldocument that is a composite image of the plurality of partial imagesand that is separately unscannable as a whole; storage means for storingthe respective plurality of partial images as respective partialdocument data, the partial images having been scanned by the inputmeans; and joint-portion processing means for recognizing reference datain response to an output of the input means, for using the recognizedreference data to retrieve joint portions of the partial document datastored in the storage means, for using the recognized reference data torecognize the joint portions, and for positioning the respective partialdocument data in accordance with the recognized joint portions, whereinthe plurality of partial images are on partial documents, the referencedata are numbers that have been preliminarily included on the partialdocuments and the joint-portion processing means detects joint portionsthat coincide among the partial document data, in accordance with thenumbers, the numbers being a predetermined color and after having joinedthe partial document data together, the joint-portion processing meansremoves the numbers from the respective partial document data using apredetermined color-omitting operation.